S3 is on Five atm but at around 1am :yawn:.
Alias is a really hard show to summarize too. Basically Sydney worked for SD-6 thinking they were a division of the CIA, but they were actually evil. She told her fiance that she was a spy and SD-6 had him killed. Her father then told her the truth about SD-6, she went to the CIA and became a double agent and discovered that her father was also a double agent. Every time she was sent on a mission by SD-6, Vaughn gave her a counter-mission which gave CIA the info and SD-6 a fake (most of the time anyway). Halfway through S2 the CIA took down SD-6 and Marshall and Dixon came to the CIA, and Syd and Vaughn got together. At the end of S2 Syd woke up in Hong Kong and was told that she had been missing for 2 years and that Vaughn had married someone called Lauren. She found out that she had been taken by the Covenant who wanted her to be Julia Thorne, an assassin. She had erased her own memory. Lauren worked for the Covenant and Vaughn killed her at the end of S3.
There is a whole thing about Rambaldi, but that's way too complicated to explain.
If you have loads of time there are detailed recaps
here, though I would quickly scroll to the bottom after clicking show all episodes since this is at US pace :)
Ah Kate beat me to it :lol: