Season 2: Episode 4 - "Dead Drop"
 

As Sydney struggles underwater, she takes the gun of a drowned henchman and fires through the ice. Dixon helps pull her through.

At the SD-6 offices, Sydney tells Sloane that although Sark got away with the music box, it was corroded anyway. Sloane wonders why Rambaldi placed the artifact in ice. Later at the CIA, Kendall refuses Jack's wish to have Irina removed. When Sydney confronts Jack, he says he worries about the emotional aspects of their dialogue and warns Sydney that she wants a mother.

Sloane tells Jack about the mysterious phone call from the B&B and has Dixon investigate. He also says that SD-6 retrieved the corroded music box from Sark's safe house in the Falkland Islands, where they also found a man named Klaus Richter, who was seriously ill from a serum that Sark had administered. Jack interrogates Richter and learns that he had designed a map to lead Irina to The Bible, which he had hidden in a remote location. The map, we learn, is hidden in a 1st edition of War and Peace in a Moscow military library.

To prevent Sydney from seeing Irina, Jack gives Sydney a fake map which will lead SD-6 to the Sunken Forest — before she's given the SD-6 mission and the CIA counter-mission. Sydney says all she wants out of Irina is enough info to bring down SD-6 and get her out of the spy game.

In rehab, Will meets Rebecca Martinez, a conspiracy theorist who presses him to continue his expose of SD-6. Will refuses. Later she meets with Sloane; she's SD-6, and was sent to test Will. Dixon then returns with the B&B registry — signed by Emily!

Irina tells Sydney how to get to the map in exchange for her earrings and expresses worry. Vaughn offers Sydney his unconditional support during this difficult time. Meanwhile, an upset Jack tells the CIA psychiatrist that he's afraid of losing his daughter.

Sydney appears in Moscow disguised as a military officer and, using an electronic skeleton key fashioned from a medal, she finds the book and retrieves the map. Suddenly Sark appears and offers her a chance to work for him. Naturally, Sydney declines and escapes Sark, only to become trapped in an office by Russian guards. Sydney desperately calls Vaughn and has him enlist Irina to get her out. Irina alerts Sydney to a secret passage, which she uses to escape.

Later, Irina decodes the map, which reveals that The Bible is in a house in Madagascar. Kendall sends Vaughn and Sydney, over Jack's objections. Jack privately hatches a plan and has the building rigged with explosives. As Sydney and Vaughn arrive, Sark's men overtake them and enter the building, which explodes. As a result, Kendall has Irina taken to Camp Harris for unrestricted interrogation. A heartbroken Sydney tells Jack that he was right about Irina and apologizes for doubting him.