Episode 10: The Index
Sydney, Weiss and Nadia discuss Nadia's upcoming birthday. Nadia doesn't want to celebrate; she doesn't even know when her real birthday is.
At the team briefing, Sloane tells them about the Blackwell Index, an encrypted disc once owned by the CIA that contains incriminating evidence against many government officials and corporate heads. The CIA was never able to crack it, and now the disc has been stolen. The team is to steal a Decoder disc housed in an evidence room in a Paris police precinct. Vaughn is passed over for the mission - he's heading to Arizona to visit his comatose uncle.
Dixon approaches Syd, saying that he refuses to follow Sloane blindly and now double-checks all information - he's even installed a wiretap in his office, and though the line is encrypted, he's traced a call Sloane made to Miles Deveraux, a former Alliance agent. Dixon then goes to Director Chase, who says he needs more proof that Sloane is reforming The Alliance. Dixon asks for Syd's help in decoding the conversations.
In the Arizona hospital, a nurse named Rosemary tells Vaughn that his uncle frequently spoke about Vaughn's father Bill. She gives Vaughn an envelope from the uncle, meant for Vaughn's father. Later, Vaughn opens a locker in a Mesa bus station and finds a diary with entries dating to 1982. Bill Vaughn died in 1979.
Syd shows Dixon a mini-disc burner, created by Marshall, which will produce a corrupted copy of the Decoder Disc. They agree to give Sloane the phony copy.
In Paris, Sydney who is dressed as an American punk, vandalizes Weiss's vehicle in order to get arrested. Dixon arrives as Sydney's lawyer and quickly shoots the guard with a tranquilizer.
Nadia remotely guides Syd to the evidence room of the police station. She finds the Decoder while Nadia scrambles the security camera. Sydney makes the corrupted copy and flees from the police. She races to the roof and leaps on to a helicopter piloted by Weiss. At APO, Syd convinces Sloane to hold a dinner party for Nadia's birthday. At the party, Syd gets a phone call from Dixon. She retreats to Sloane's office and transmits Sloane's decoded conversations with Devereux. The conversation revealed Sloane's contact with Deveraux, and an implied reformation of SD-6. As Syd is about to leave, she sees Nadia standing before her. Nadia accuses Syd of using her but Syd enlightens her. Dixon, armed with the decoded conversations, convinces Director Chase that Sloane's must be taken down.
In Brussels, Sydney, Nadia, Dixon and Chase observe Sloane as he enters an abandoned building. Inside, Deveraux presents the Blackwell Index, which is to be cracked using the decoder that Sloane now has, to a group of men.
Sydney, Dixon and Director Chase run into the building, leaving Nadia to wait for them in the car. As the three burst through the door, they find Sloane alone in a deserted room, with a laptop. They discover that Sloane is actually conducting surveillance as Jack meets with Alliance members. Syd realizes that Jack has the false Decoder just as Devereaux begins to doubt Jack. Nadia speeds to the meeting and arrives in time and takes out the Alliance members, saving Jack's life.
Miles away, Vaughn tries to speak with his comatose uncle. "Is he still alive?" Vaughn asks. No answer. Vaughn asks the head nurse if he can speak to Rosemary. The nurse says nobody by that name works there.
Sloane, in his home office, inserts the Decoder Disc into his laptop, revealing the Blackwell Index. He then calls Jack and tells him it has everything they need -- and more.
- description from ABC.com