The first book of the Counter Earth saga, in which we are introduced to the protagonist, Tarl Cabol, a british History professor who is abducted by a mysterious silver ship and transported to the world of Gor. After being trained in the methods and ways of his new world, he embarks on a mission to steal the Home Stone, or symbolic "seat of power" of the city of Ar, a great Gorean city-state with ambitions of imperial mastery. To do so he tames a mighty tarn, or Gorean riding bird, which he names "Ubar of the Skies," and becomes an expert "tarnsman" from which the book takes its title. During his mission he encounters Talena, daughter of Marlenus, the "Ubar" or king of Ar. Though his mission is successful he has difficulties which result in several adventures, including an encounter with Nar, an intelligent Swamp Spider of Gor, a brief stint as the guard of a slave caravan, and several attempts on his life, all of which fail. He eventually finds himself embroiled in a duel to the death with Pa-Kur, the Master of the caste of Assassins, who has attempted to seize control of Ar after Marlenus' has been deposed. Tarl winds up defending Talena with Marlenus atop the Cylinder of Justice in Ar, while armies clash in the streets below and tarnsmen duel in the skies overhead. After Pa-Kur is defeated, Ar is placed in the hands of Kazrak, a friend of Tarl's, who will serve as its Administrator, and Marlenus is banished from his former city. Tarl and Talena become Free Companions, the Gorean term for formal consorts; but that very night Tarl falls asleep in her arms, only to awaken upon Earth, at the precise location where he was first abducted. He pledges to write down his story, assuming no one will believe him, and swears one day to see the manuscript published. He refuses to forget Talena, nor his brief visit to that other world.

     This book starts seven years after the end of the first. Tarl has tried to reassimilate himself back into Earth society with little success. One night, after an extended drinking bout, he returns to his apartment, locking the door. Harrison Smith, an earth friend of his, enters the apartment sometime later, finding it empty, with a manuscript upon the coffee table, entitled "Tarnsman of Gor". Of Tarl, there is no trace. Tarl, it turns out, has been once again abducted, and has returned to Gor. Throughout the series he never again sets foot upon Earth. Once upon Gor he sets out to return to his adopted city of Ko-ro-ba, only to discover that it has been destroyed during his absence and all of his friends and former colleagues from there have been scattered across Gor by the Priest Kings, the mystical rulers of that planet. Tarl sets off to enter the Sardar mountains, home of the Priest Kings, but enroute is captured and forced to compete in the brutal gladatorial sports of the city. Despite his victory there he is impressed into slavery in the silver mines of the gynocratic city of Tharna. He resists captivity, inspiring a slave revolt, and captures Lara, the Tatrix (female ruler) of the city. Attempting to ransom his other companions, including the singer Andreas of Tor and the metal- worker Kron of Tharna, he and Lara are both betrayed by the Lady Dorna, who with the aid of her warrior-henchman Thorn replaces Lara as Tatrix of the city. Forced to fight against his friends in another gladitorial match for the amusement of the new Tatrix, Tarl and his companions again escape, resulting in a civil war between followers of Lara and those who serve Dorna. In the end, a much kinder and gentler Lara is restored to her throne, Thorn dies in a duel with Tarl, and Dorna escapes via tarnback, her final fate uncertain. Tarl takes leave of Tharna, arriving at the gates to the Sardar. He enters the foreboding mountains, determined to confront the Priest Kings and avenge his ruined city.

     This book opens with Tarl entering the great gates which mark the entrance to the Sardar mountains. After a perilous climb and a deadly encounter with a trained pair of white snow-larls (Gorean saber-toothed tigers) he finds the entrance to a great underground complex, the lair of the Priest Kings. Though welcomed by Parp, an odd human who claims to be a Priest King, Tarl is not so sure. After resisting an attempt by Vika, a former freewoman who is now a slave of the Priest Kings, to rule him through femine wiles, he further explores the complex and there encounters Misk, a true Priest King: a ten foot tall, gold colored insectoid being with highly developed intelligence and incredibly advanced technology. Tarl learns from Misk that Ko-ro-ba was destroyed simply to lure him to the Sardar mountains, and that another of the Priest Kings, Sarm, is planning to seize control of the "Nest", or hive-like complex, and in so doing conquer all of Gor, enslaving all humans as mindless servants of the Priest Kings' will. Tarl also befriends Al-Ka and Ba-Ta, two "muls" or nest-bred human servants of the Priest Kings, who have been cloned one from the other. Sarm tries to force Tarl to assassinate Misk, but Tarl refuses and rescues both Vika and Misk from Sarm's plot. A great conflict, or "Nest-War" begins, in which most of the human inhabitants of the Nest join forces with Tarl and Misk to battle the servants of Sarm for control of the complex. In the end Sarm falls victim to his own treachery, but not before he attempts to sabotage the Nest's power generator, thereby destroying the entire planet. Misk and his followers are able to prevent this from happening, though during the process the offspring of one of the last two eggs of the Priest Kings, a male capable of impregnating a Mother Priest King, is threatened, but saved, and Tarl himself is nearly slain by the larls at the mountain entrance. Parp sacrifices his life to save Tarl, and it is revealed he was Vika's father. Tarl is sent by Misk to the plains of the wagon peoples to recover the final surviving egg, a female who might become the new Mother of a renewed race of Priest Kings, hidden somewhere among that distant land, in the hopes that the extinction of the Priest Kings might somehow be averted.

     This book begins with Tarl's arrival in the lands of the Wagon Peoples, the Gorean equivalent to the Mongol Tribesmen of Earth. After he earns entrance into their culture through trial-by-combat he joins the Tuchuk tribe and befriends Kamchak, a Tuchuk warrior. A slavegirl is captured by the Tuchuks, an Earth girl named Elizabeth Cardwell. Tarl speaks to her in english, revealing himself as a man of Earth. She wears a message collar which contains a secret message upon which are instructions to kill Tarl, supposedly from the Priest Kings. Tuchuk and Kutaituchik (Ubar of the Tuchuks) refuse to comply, correctly deducing that it is a trick. Tarl realizes for the first time that there are perhaps others who possess equal technology to that of the Priest Kings, and who seek to destroy the Priest Kings and seize control of Gor. Tarl and Kamchak visit the huge, walled city of Turia, and there make the acquaintance of Saphrar, a merchant, and the mercenary tarnsman Ha-Keel of Port Kar. During this meeting it is revealed that Kamchak is pursuing the affections of the haughty freewoman Aphris of Turia, who scorns him. Shortly thereafter Aphris is won by Kamchak in the Turian Love Games, and is reduced to slavery. All is well until a sudden attack upon the camp of the Tuchuks by mercenary tarnsmen, which results in the death of Kutaituchik, reveals that there are enemies among one of the other tribes who seek the egg of Priest Kings as well. Kutaituchik, it is revealed, was a decoy; Kamchak has always been the true Ubar of the Tuchuks and summons the other tribes to fight alongside the Tuchuks against the Paravaci tribe, who are now known to be working with the Turians against the other wagon peoples, as well as against the Priest Kings themselves. While Turia is under seige, Tarl sneaks into the walled city, aided by by Harold of the Tuchuks, a former Turian slave who has become a fierce Tuchuk warrior. Tarl and Harold are captured and thrown into the "yellow pool of Turia," actually a living entity which paralyzes and digests the bodies of any who are immersed in it. Tarl manages to prevent the creature from devouring he and his comrade and the two escape. A great battle ensues in which the Paravaci are conquered and Turia is successfully invaded by the warriors of the wagon peoples. A quarrel between the traitorous Ubar of the Paravaci and Saphrar leaves the Paravaci dead by poison. Saphrar himself, attempting to flee, falls into the yellow pool and meets a grisly end. The stolen egg of the Priest Kings is also revealed to have been fraudulent...Kamchak produces the genuine article, and Tarl and the earth girl Elizabeth (now called Vella) leave the lands of the wagon-peoples to return the egg to the nest in the distant Sardar Mountains.

     This book opens with the introduction of Kuurus, a member of the caste of Assassins, who has been hired to avenge a murdered warrior. The dead warrior, we learn, is Tarl Cabot, and Kuurus travels to Ar to seek Tarl's murderer. Kuurus, it turns out, IS Tarl Cabot; and along with Vella has been sent by Misk to investigate the presence of the "Others": beings who possess super high technology and contend with Priest Kings for control of both Earth and Gor. Once in Ar, Tarl, still in disguise, infiltrates the House of the slaver Cernus where he learns that Kazrak, Administrator of Ar and Tarl's friend, has been deposed and that Ar is now ruled by Minus Tentius Hinrabius, a nobleman of the caste of builders. The House of Cernus, it seems, has recently acquired a monopoly on the slave trade of Ar through control of an odd influx of "barbarian" earth slaves. Suspicious of Cernus' source of such otherworldly merchandise, Tarl gathers information for the Priest Kings about the unusual practices of the House of Cernus. Meanwhile, he also poses as "Gladius of Cos", a masked tarn-rider who competes weekly in the races at the Stadium of Tarns. During this time, Tarl and Vella also meet Ho-Tu and Sura, slaves of the house of Cernus, and they have several encounters with Hup the Fool, a thieving dwarf who seems utterly devoid of intelligence. Vella, meanwhile, has befriended a pair of earth girls, Phyllis and Virginia, now also slaves in Cernus' pens. Tarl also learns of a popular new gladiator named Murmillius, who always fights masked and has never been beaten. As Tarl cautiously explores the house of Cernus over a period of several months, he discovers a mysterious chamber which is always kept locked; within it, he is informed, dwells a "beast", a savage creature which can tear a man apart in a matter of seconds. Tarl's mission seems to be going well until Cernus stages a coup d'etat with the aid of his ill-gotten fortune and the support of the Taurentians, or Ubar's personal guard. On the orders of Cernus, Hinrabius is deposed and the slaver crowns himself Ubar of Ar. Tarl is immediately taken into custody as a spy; Cernus, it turns out, has known his true identity all along. Vella and her two companions are carted off to the Curulean slave block to be sold to the highest bidder, who turns out to be Samos, dreaded first slaver of Port Kar. Tarl is brought before Cernus in chains, and offered his freedom in exchange for a wager: a game of kaissa will be played, and if Tarl wins, he will be allowed to live. Cernus will not play himself; therefore Tarl must choose a champion also. Cernus' champion turns out to be the legendary, crippled Scormus of Ar, who has never been beaten at Kaissa. Tarl's choice is made for him by Cernus: Hup the fool will play Kaissa against Scormus, championing Tarl's life. It seems as if Tarl is doomed, but amazingly Hup defeats Scormus. Hup, it seems, is actually brilliantly intelligent and an agent of the Priest Kings, as well as being Scormus' father. Furious, Cernus sends Tarl into the Stadium of Blades to be slain in gladiatorial combat. Tarl is saved by Murmillius... who reveals himself to be Marlenus, exiled Ubar of Ar. Together, Tarl and Marlenus win the day and set out to dethrone Cernus, Marlenus by seizing the reins of power, Tarl by publicly humiliating Cernus by defeating his tarnsmen in the Stadium of Tarns. Upon his triumphant return to the house of Cernus, however, Tarl discovers that Sura has committed suicide, no longer willing to live as a slave. Ho-Tu, who was in love with Sura, joins Tarl as he confronts Cernus. A duel follows, and the wounded slaver flees. Ho-Tu, learning of Sura's death, takes his own life. Tarl follows Cernus, only to discover that the former-Ubar has been slain by the "beast," which has escaped on tarnback. Tarl discovers some sort of communications device left behind by the creature, revealing that the "beast" was in fact one of the "Others" about which Misk warned him. The book ends with the restoration of Marlenus to the throne of Ar, all three slaves including Vella safely returned to Tarl and his companions by Samos (who, we suspect, may be an agent of Priest Kings), and Tarl being summoned before Marlenus to receive his just rewards. The Ubar "rewards" him by banishing him from Ar upon pain of death, never to return. Tarl understands this... it is only fitting, since Tarl's own actions in the first book resulted in Marlenus' loss of the throne to begin with. Nevertheless, Tarl is happy; he officially frees Vella, and the two board his own tarn, Ubar of the Skies, to return to the Sardar and report the success of their mission.

     This book begins with Tarl enroute to the infamous pirate city of Port Kar, poling a boat through the vast marshes of the Vosk delta. Vella, informed that she was to be returned to earth for her own safety, has fled, taking the mighty tarn Ubar of the skies with her, nor has she been seen since. Tarl angrily drove the bird away when it returned without her. Now he is going to Port Kar to meet with Samos, the Master Slaver of Port Kar, said to be an agent of Priest Kings. While enroute he is ambushed by rencers, the fierce denizens of the marshes, and is sentenced to death for trespassing in their domain. Rather than accepting his fate, Tarl begs for his life, in violation of his Warrior Codes, and is taken slave. His mistress is Telima, once a slave in Port Kar but now an escaped freewoman of the rence. A few days later, however, the floating rence-islands upon which the rencers dwell are attacked by slavers from Port Kar. Tarl makes his escape and brings Telima with him to safety. Thereafter he wages a one-man war with the slavers as they try to transport their slaves from the marsh, until all of the slavers are dead or have fled. Tarl then frees the male oarsmen from their barge chains and invites two of them, Clitis the Fisherman and Thurnock of the Peasants, to join him. He keeps Telima as his personal slave, as well as several other rence-girls who formerly tormented him. He frees the other rencers, but he has lost his honor. Taking the name Bosk of Port Kar, he leads his men and slaves to Port Kar, and settles there, abandoning the service of Priest Kings. Once there he slays the pirate captain Surbus in a duel and assumes command of his ships and crews. He encounters Samos of Port Kar, but does not inform him that he was once Tarl of Ko-ro-ba. Sent on a dangerous spying mission, Bosk is taken captive by the Cosians but is swiftly rescued by his own men. During this time, the navies of Cos and Tyros are beginning to threaten Port Kar. After the five rival co-Ubars of that city are attacked, Bosk takes one of them, young Henrius Sevarius, as a slave, naming him Fish and allowing him to hide in his house in relative safety. The ships of Bosk sack a mighty Cosian treasure fleet, insuring the financial security of the House of Bosk for years to come. Though Bosk prospers, he is unable to find happiness; when Midice, his preferred slave, betrays him by falling in love with Tab, one of Bosk's men, Bosk breaks down; it is then that he discovers that Telima and he have long since loved one another. Port Kar discovers that the joint fleets of Cos and Tyros are planning to attack and destroy the city; many flee, but Bosk chooses a Home Stone for the beleaguered city, and armed with the potent symbolism that Port Kar now has a Home Stone, rallies the Council of Captains to defend the city at all cost. In the huge sea-battle which follows, the fleet of Port Kar makes use of sea-borne tarn divisions, a new strategic method, and smashes the combined fleets of her enemies, taking Chenbar, the Ubar of Tyros, prisoner in the process. Upon returning to Port Kar, however, Bosk and Samos, now allies, discover that their personal strongholds are under attack by the two of the former Ubars of Port Kar and their men. A prolonged seige follows, but just as it seems the houses of Bosk and Samos must fall, the beseiging force is attacked and destroyed by the rencers, who are led by Ho-Hak, a former galley slave and rencer who Bosk rescued earlier in the book. At the end of the book it is revealed that Samos was once the master of Telima, and that he allowed her to escape and arranged to have Tarl enslaved in the delta, thus creating "Bosk" from the shattered remnants of Tarl's lost honor. Bosk responds to this by vowing never again to serve the Priest Kings or their agents, though he and Samos remain friends, and though he is still unable to forget his first love, Talena, he and Telima remain together and he finds contentment, at least for the time being.

     This book is written almost entirely from the viewpoint of Elinor Brinton, a wealthy socialite from Earth who finds herself abducted by slavers from Gor. It describes in great detail the manner of her capture and training as she is transformed from a stiff, haughty Earth woman into an exquisite Gorean slavegirl. Her repeated attempts to violate Gorean customs, her pettiness and betrayal of the fellow slavegirls who attempt to instruct and aid her, are all well documented... for these offenses she is finally subjected to a penalty branding, in which symbols are burned into her body marking her as a liar, thief, and traitress. In particular, this book details her relationship with the tarnsman/slaver Rask of Treve, as well as describing the "talunas," or panther girls, of Gor, who live free in the vast unexplored northern forests. One of these panther girls, named Verna, takes Elinor captive, and in the camp of Verna it is revealed that Talena, Tarl's former free companion, has been enslaved and purchased by Rask of Treve, as an insult to her father Marlenus, Ubar of Ar. Verna, who seeks to lure Marlenus to the northern forests for her own reasons, acquires Talena and takes her there to await such an expedition. Though it seems as if Rask of Treve cares for Elinor, he insists upon selling her. She is auctioned at the Cuerulan slave block in Ar, and spends several months serving in a paga tavern before she is purchased and shipped to Port Kar. There she discovers to her horror that Rask has been captured by agents of the "Others," and will be slain unless Elinor assassinates the warrior/merchant Bosk of Port Kar by poison. She is unable to commit the deed, though Rask escapes. At the book's end Elinor has at last accepted the fact of her slavery and has fallen in love with Rask, though it seems unlikely she will ever see him again. Her narration concludes with a notation that it was written by Elinor at the command of her Master, Bosk of Port Kar. At this point Bosk himself takes over the narration, explaining that Rask of Treve assaulted his house and abducted the girl shortly after Elinor completed her writings, but that Rask had left behind a bag of gold as payment, and there would be no attempt at reprisal. The book concludes with Bosk's pledge to enter the northern forests and recover Talena at all cost.