Alias (season 4)

The fourth season of Alias follows Sydney Bristow as she leaves the CIA and joins a covert black ops unit called Authorized Personnel Only, working alongside Jack, Dixon, Vaughn, and even Sloane. The season begins with Sydney uncovering shocking secrets about her past, including the truth about her mother and the mysterious S.A.B. 47 Project, which puts her relationship with Jack under strain. Sydney and Vaughn continue to face dangerous missions, including infiltrating a training camp run by the October Contingent and intercepting a deadly bioweapon called Ice Five that can crystallize water in the human body. As the season progresses, Sydney and her team confront the return of Elena Derevko, who has been tracking Sydney and Nadia. Jack and Sloane reveal that Elena is alive and orchestrating a plan involving the Mueller Device, which causes mass violence in a Russian city. The team races to stop Elena and Sloane, with Sydney ultimately disarming the device while Sloane saves her by shooting Nadia, who is under the device's influence. Irina Derevko is freed and helps Sydney shut down the device just in time. Vaughn discovers clues about his father's survival and is manipulated by Sloane, who hires a man to deceive him. Sydney and Vaughn's relationship deepens, and he proposes to her before they parachute into the city to stop Elena. The season ends with Sydney and Vaughn on a romantic getaway, but Vaughn reveals a shocking secret about his true identity just before they are involved in a car accident. Meanwhile, Sloane is imprisoned for his actions but is later released due to political influence, and new agents join the team as the story continues to unfold.