Complete story — includes the ending
While searching for Vaughn's father, Vaughn and Sydney discover that Nightingale is a molecular manipulation weapon system located in a nuclear reactor in Siberia. Sloane and Jack know about Nightingale and its connection to Elena Derevko. The duo later use Sydney to have Vaughn bring the information to APO and thus make it an official mission. Meanwhile, a mysterious stranger, Roberts, meets with Vaughn in the UCLA library and promises answers about his father in exchange for the Nightingale's coil. Vaughn, Sydney and Jack travel to the Nightingale facility to shut it down and retrieve the coil from the weapon, however, Sydney becomes trapped in the room with the Nightingale device. From three different locations, Jack, Vaughn and Marshall attempt to free her. Ultimately Jack shuts down the nuclear core manually exposing himself to harmful radiation. With Sydney's help, Vaughn disappears with the coil to learn more about his father. Marshall discovers what Jack did, but swears to keep Jack's secret.
Sources and content license
Source and revision history · Adapted from Wikipedia contributors, Alias season 4. HTML formatting and reference markers removed. · Content license