Vaughn and Sydney must destroy a Rambaldi artifact to save Will. Jack makes a deal with Mr Sark, and The Alliance decides the fate of Emily Sloane.

Sydney and Dixon must go to a Paris nightclub, where Sark will deliver the ampule to Khasinau. Dixon is to steal pages of a Rambaldi manuscript.

Sydney and Vaughn meet with Mr Sark hoping to catch Khasinau, but Sydney's cover is endangered when an SD-6 agent is sent to stop the trade.

Vaughn confirms that K-Directorate has hired an assassin, known as "The Snowman" for his favored use of an ice pick as a weapon, to take out Khasinau.

Sydney is reunited with Noah Hicks, an SD-6 agent she dated five years ago.

While being questioned by the FBI about her ties to Rambaldi, Sydney makes a shocking discovery that may unravel the mysterious 500-year-old prophecy.

The Department of Special Research inquires about Sydney's connection to the Rambaldi notebook.

Sydney and Dixon are dispatched to Tunisia. A Rambaldi manuscript is being held on a yacht, and their mission is to retrieve it before Sark gets it.

Sydney and Dixon travel to Las Vegas to try and track down the group that nearly destroyed SD-6.

Sydney discovers a note left for her by her father, explaining the dire predicament: opening the SD-6 vault would trigger a fatal explosion.

A group of heavily-armed intruders sneak into SD-6 and take control of the building.

After Jack saves Sydney during a mission, she discovers that he was responsible for the deaths of many CIA agents, complicating her feelings for him.

Jack must save Sydney when Sloane orders her to be tortured and killed after she is suspected as the mole. Sydney tells Vaughn about her time at SD-6.

Sydney is scared, as she thinks that Dixon may have heard her talking to the CIA.

Sydney travels to Oxford to steal an ancient clock connected to the Rambaldi mystery.

Sydney learns about Shepard's involvement in her past. Sloane confronts the Alliance about the CIA bug, and they conclude that SD-6 has been moled.

Sydney forms the opinion the Jack's suspicious activities led to the death of her mother 20 years earlier, creating a deeper tension between them.

Will tells Francie that he's been investigating the death of Danny. Sydney learns from Vaughn that her father may also be working for the FBI.

Sydney and Anna memorize a code written by Rambaldi. Sydney and Dixon are sent to investigate a plot to eliminate the United Commerce Organization.

Sydney and Dixon go to Madrid to steal a lockbox containing a sketch with what appears to be a digital code drawn by a 15th century seer, Milo Rambaldi.

In her new role as a double agent for the CIA, Sydney is intent on destroying SD-6 within weeks.

Sydney Bristow is a college student who leads a double life: she works for shadowy government agency called SD-6 which is supposed to be a covert branch of the CIA and reports to Arvin Sloane. Recently engaged, she tells her boyfriend, Danny Hecht, the truth. The next day, he is murdered. Later, Sydney's father, Jack Bristow, tells the truth: he is a double agent for the real CIA, as SD-6 is a renegade agency who allegedly killed Sydney's fiancé. Sydney must make a decision which will haunt her for the rest of her life. Sydney's partner in the field, Marcus Dixon, is also unaware about his true alliances as is SD-6's tech expert, the socially awkward Marshall Flinkman. Sydney's friends, the headstrong Francine, and the ambitious journalist Will Tippin are also unaware about Sydney's double life, until Will becomes inquisitive about Sydney's well-being following her fiancé's murder.