Irina tells Sydney that Sark is after a Rambaldi-designed music box. Encoded in the tune is a numerical equation for 0-Point Energy. Sydney rebuffs Irina's attempts to talk about her childhood. Later, Jack warns Syd about Irina, but says he trusts her judgement.

Marshall gives Sydney a hydraulic luge disguised as a suitcase. A grieving Sloane gives her something more personal: Emily's seed box. As part of her counter-mission, Vaughn gives her a circuit board to attach to the camera and suggests bringing in Will, who's been staying with Syd and Francie, because he may remember the code Sark was working on that activates the music box. When they do meet, Will is surprised at Vaughn's youth and is jealous at how much he knows about their lives.

In Sri Lanka, Sydney disguised in a red wig as a European business woman, appears at the launch facility as Dixon breaks down the surveillance. She then dons a worker's jumpsuit and luges through the exhaust ports to the launch deck. A suspicious Sark speeds the launch. Syd barely completes wiring the circuit board and lugs out at 125 mph. The camera locates the music box in the centre of a Siberian ice cavern.

Under hypnosis, Will remembers the names on Sark's computer — Dosteyevsky, Nabakov, Tolstoy, Checkov. Vaughn notices Sydney's feelings for Will. Later, Irina decodes the names and warns Sydney about Sark's ruthlessness, saying she wants the chance to explain herself.

Sloane receives a ghostly call from the Baranka B&B in Sonoma, CA — where he an Emily were supposed to go before she died.

Jack confronts Irina, who says they had their good moments together. He threatens to kill her if Sydney is harmed. She asks cryptically, "You haven't told her what you did to her after I disappeared, have you?"

In Siberia, Sydney receives the code from Vaughn and plays the music box. She records the tune and acts to disable the artefact. The SD-6 team is ambushed by Sark's men, however, and Sydney falls under the ice.