Season 1: Episode 13 - "The Box (Part 2)"

Sydney is hiding in the air ducts as McKenas Cole blasts away at the ceiling when suddenly Jack appears and surrenders, allowing Sydney to remain hidden.

Sydney discovers a note left for her by her father, explaining the dire predicament: since Sloane has activated the fail-safe alarm, opening the SD-6 vault would trigger a fatal explosion. Before the intruders can hack the vault security code, Sydney must disarm three charges of C-4.

Meanwhile, Dixon manages to swipe a PDA from a desk, and secretly sends an e-mail to the CIA. Vaughn gets the message but Agent Haladki, now in charge of the SD-6 case, refuses to send a rescue team without more proof of an attack.

Against official orders, Vaughn goes to Credit Dauphine and confirms the break-in to Haladki, who again refuses to send help. Vaughn then meets up with Sydney and helps her disable the first charge of C-4. They split up to disarm the two remaining charges.

Cole realizes that someone is still loose in the building and broadcasts an order through the address system: if Sydney doesn't surrender, Cole will begin killing the hostages. He chooses Jack as the first victim, and Sydney surrenders before she can disarm the C-4.

After Sydney is taken hostage, Marshall signals to her that one of her earrings, lying on the floor, is actually a flash grenade. She detonates the device, overpowering the intruders in the ensuing chaos.

Meanwhile, the key that Will was given leads him to a locker containing an autopsy report on David McNeil's wife. Her death was allegedly a suicide, but the new evidence suggests otherwise. Will urges Kelly McNeil to go into hiding.

At the CIA, Agent Weiss learns of Vaughn's call and sends a rescue team. Jack finds Sloane in the SD-6 torture room. Only Sloane can deactivate the fail-safe, but his fingerprint is needed as verification. Both men realize that the only way to save the SD-6 is to cut off Sloane's finger.

Using the bloody digit, Jack cancels the fail-safe order seconds before Cole opens the vault. Once inside, Cole removes a small metal box, marked with the Rambaldi symbol <0>. As he tries to escape, Cole is captured by Sydney and the CIA rescue team. Vaughn opens the metal box and finds a small vial of clear solution.

SD-6 now believes that the break-in was successful, not realizing that the Rambaldi artifact is with the CIA. But mysteries remain. Who has McKenas Cole been working for? And what secrets will the mysterious liquid unlock?