From JJ Abrams, the director of Lost and Star Trek. Alias stars Jennifer Garner. Well worth a look if you've never seen it before.
Amazon also have Season 4 for around the same price, but the other seasons are more expensive than HMV (and you can get 5% Quidco with HMV). HMV and Amazon also have the complete box set for around 55 quid if you want the whole lot.
Jennifer Garner stars in this television series as Sydney Bristow, a 26 year-old graduate student working for a secret division of the CIA. The mission of this arm of the CIA is to combat SD-6, a secret terrorist organisation whose agents believe that they, in fact, work for a secret organisation of the CIA that combats terrorism. This first season of the series begins as Sydney begins work as a double agent for the CIA, who want to destroy the organisation and its leader, Arvin Sloane. Sent all over the world on various undercover missions, Sydney must sabotage SD-6's efforts while maintaining her cover so that she can help take down SD-6 from the inside. Quite possibly the most entertaining show to debut on television in the last decade, ALIAS is a fast-paced thrill ride buoyed by Ms. Garner's performance as well as her penchant for wearing some outrageously risque disguises on her missions.