This is the third in a series, the first two being The Lion of England and The Lion of Justice.  I haven't read the others, but from the reviews on the back of the book praising the author's other works I gather that the first one is mostly the story of Henry and the second covers the beginning of the quarrel.
 

Thomas is already in exile in Flanders when the book begins.  His people and Henry's people both visit King Louis.  Thomas moves to Pontigny and falls ill but recovers after diseased bone is removed from his jaw.

Meanwhile, back in England, Cicely, the bastard daughter of Richard Fitzurse, is inducted into the Old Religion (the one constructed by Margaret Murray).

There are more political negotiations in the Thomas/Henry struggle.

Reynold Fitzurse (son of Richard) pursues a gang of Ranulf de Broc's cutthroats and encounters an old wisewoman who offers to tell his future or grant a wish.  He wishes that his name might live a thousand years.  He intends it as a wish for a son, so that his family name will endure, but of course we know his name will live for entirely different reasons.

John of Salisbury and Herbert of Bosham visit Henry, who has problems on all sides: Thomas, the Welsh, etc.  He meets Rosamund de Clifford, who will become one of the great loves of his life.

Hugh de Morville boils one of his serfs alive as punishment for something.  While riding around, the four knights (yes, those four knights) find Cicely and her boyfriend in the fields, chase them for sport, kill the boy, and rape Cicely, who is suffocated when they wrap her head in her skirts to control her.  And just when you thought things couldn't get any worse, the rapist is Reynold, Cicely's half-brother (although he didn't know it because their father refused to acknowledge her).

Henry the Young King is crowned.

From Christmas on, we follow events day by day and see the movements of Thomas and the knights.  Thomas is murdered.  Henry is sorry.  End of story.

Personally, I found this book somewhat flat.  This is not necessarily a reflection of its quality, just of my personal preferences.  I often have this problem with historical novels, because they're usually focused on what happened, whereas I like to see what people are thinking.  Not that we're never privy to people's thoughts in this book, but it's not the same as when we're focused on one protagonist instead of skipping from place to place and person to person.

I do like the way the description Thomas's last few days is drawn out, as if time has slowed down as the crisis approaches (the whole book covers six years, which necessitates frequent leaps over great gaps of time).  You have to admit that being murdered is what made him interesting - otherwise the whole affair would have been just another medieval quarrel.  And the drama of the event itself appeals to me.

There's a small theme of the importance of one's name being remembered.  Fitzurse is preoccupied with the matter, and Thomas wonders if leaving behind some accomplishment, a work of art, matters at all if the artist's name is forgotten.

The appearance of Vivian, a papal legate, prompts me to think about how some names have changed genders over the centuries.  Besides Vivian, there's Hilary of Chichester and Jocelyn of Salisbury, and those are just the names connected with the Becket story.  There are other, more recent examples, like Courtney, which is still on the tail end of tranforming from male to female.

Here's a site on the etymology of first names, and here's an amusing one on bad names.