Before The Flood is the 22nd episode of Season 4 of Alias, the 88th episode overall and the Season 4 finale. Jack, Sydney, Irina, Vaughn and Nadia parachute into Sovogda in an effort to dismantle the Mueller device threatening the city. At APO, Marshall and Weiss use the Blackwell Index to blackmail the Russian minister into giving them the access codes to a Russian satellite. Whilst doing so, they discover that Elena is uplinking the satellite. A CIA agent, Brodien, reminds the crew in Sovogda that the Rambaldi device is broadcasting a subaudible frequency that physiologically alters people who drink it and it is irreversible.