Syd and Vaughn arrive at the bunker only to find it ransacked and the elixir missing. Vaughn begins to retrieve and upload any available data to Marshall. They find video files revealing Nadia Santos as a young girl, recording messages while under a trance. Russian guards, led by Katya Derevko, surprise them. She turns on the guards, however, and tranquillises them. She reveals herself to be Syd's aunt then orders them to wear the guard uniforms. They run barrel through a checkpoint and escape.

In St. Petersburg, Katya says Lauren and Sark took the elixir. She reveals that the young Nadia was taken from that lab by Vaughn's father before she could complete the message. Katya, working with SRV (Russian Intelligence), says Irina gave birth to Nadia in a Russian prison after she left Jack. Katya has been helping Irina to locate Nadia ever since and is dismayed to hear that Sloane has her.

Sark and Lauren deliver the elixir to Sloane in exchange for a partnership. Sloane reluctantly accepts, and administers a does to Nadia to prove that she's The Passenger. Marshall, meanwhile, explains to Syd that the fluid contains potentially toxic proteins that trigger a muscular memory, forcing Nadia to relay the message. The memory is genetically stored only in descendants of Rambaldi. They view an old videotape wherein Dr. Jong Lee, aka Suit and Glasses, injects Nadia with the elixir. Dixon reveals that Lee was in charge of conducting Russia's Passenger experiments. He's now in a Cuban bio-weapons facility.

Jack warns Vaughn not to let his thirst for revenge against Lauren endanger Sydney. He gives Vaughn a key to his well-armed security facility -implicitly suggesting he kill Lauren.

While Jack and Katya track Sloane's bank withdrawals, he rebuffs her advances. He notices that Sloane made a large payment to a Dayton Electrical, a company that did electronics work in Chamonix. Jack makes the connection and visits Toni Cummings in prison. When Jack agrees to reduce her sentence, Cummings tells Jack that she drew up specs for a system for Sloane but doesn't know where he built it.

In Cienfuegos, Cuba, Syd and Vaughn find Dr. Lee. He says Nadia drew coordinates that would lead to Rambaldi. Vaughn tortures him by dripping acid on his leg. Sydney is shocked and appalled.

Marshall works with Cummings to get a delivery nexus for parts to Sloane's system. Cummings unsuccessfully tries to convince Marhsall to work for her. Marshall finds that Sloane's system is in Japan. She says she needs to travel there to determine which of the seven security variables she'd given Sloane is being used.

In Sloane's Kyoto estate, Sark urges him to increase the dosage to Nadia, who's building up a tolerance, even though it might kill her. He refuses. Sark kills Sloane's guards and Lauren ups the dose. Just then, Cummings hacks the security system and the CIA storms the compound. Sloane escapes while Syd tends to Nadia. Vaughn chases fruitlessly after Lauren and Sark, leaving Syd to dispatch Sloane's guards herself. Nadia shoots a guard about to kill Syd. They recover the drawings and texts and escape.

Dixon says Vaughn allowed Sloane to escape. Syd covers for Vaughn, despite her anger. He says she got Nadia and that's what counts. Syd says they can't work things out until he deals with his anger. Jack visits Katya and plants a kiss on her. Vaughn goes to Jack's storage facility and chooses a sniper rifle from the array of weapons.