Alias is an American action/drama television series created by J. J. Abrams which was broadcast on ABC from September 30, 2001 to May 22, 2006, spanning five seasons. It starred Jennifer Garner as Sydney Bristow, a CIA agent, who was usually seen wearing a colorful new disguise while undercover in some part of the world.
A major plotline of the series was the search for and recovery of artifacts created by Milo Rambaldi, a fictional Leonardo da Vinci-like inventor and Nostradamus-like prophet from the Renaissance period. This plot and some technologies used in the series pushed Alias into the genre of science fiction.
Sydney Bristow was recruited as an undergrad to work for SD-6, which she thought was a government agency. However, when her fiancé is killed by SD-6 agents, she finds out that SD-6 is actually a counter-government agency. Sydney approaches the CIA and becomes a double agent, which means that she goes on SD-6 missions, but passes the information about her missions to her CIA handler, Vaughn.
Sydney's father, Jack Bristow, is also an double agent. Both had a distant relationship for years, but their present situation brings them closer together. Sydney and her father spend the first season trying to foil SD-6's missions and preventing them from getting their hands on what they are determined to get. For years SD-6 has fought against FTL and K-Directorate, two crime organizations that are also in the pursue of various artifacts build by the 15th century scientist and prophet, Milo Rambaldi. However, when a new player referred to as "The Man" comes to town, FTL and K-Directorate are put out of business and SD-6 engages in the pursue of this new mysterious opponent.
After eliminating SD-6 and all of the other SD cells, Sydney, Marshall, Dixon, Jack, and Vaughn are now fully working for the CIA.