A great movie!
Slightly cheaper than the Amazon deal.
Granted, it's not in the 2 for £15, but there are plenty of blu-rays on HMV for less than £8, so you could get yourself another great one for less than £15 :)
If you haven't already, I highly recommend you watch Firefly if you get the chance!
"Beloved television cult director Joss Whedon ('Buffy The Vampire Slayer', 'Angel') makes a spectacular first foray onto the big screen with 'Serenity', the cinematic adaptation of his wildly popular but short-lived sci-fi series, 'Firefly'. A mix of space western, comedy, and drama, 'Serenity' follows captain Malcolm Mal Reynolds (Nathan Fillion) and his ragtag crew as they trade their way around the edges of civilised society. Of particular interest are two passengers they take on, Simon and River Tam (Sean Maher, Summer Glau), a brother and his telepathic sister on the run from the corrupt governing Alliance. As notorious former members of the anti-Alliance opposition, Mal and his crew make it difficult for Simon and River to stay hidden. Everything goes completely awry when a government assassin is sent to retrieve River. As Mal is forced to choose between his close-knit crew and the brother and sister newcomers, it becomes apparent that River harbours both a dangerous secret and astounding fighting powers, and Mal decides that discovering the truth about what she knows might just be worth his time. Many of the film's action sequences revolve around Summer Glau's martial arts skills in her portrayal of River. Glau prepared for her role with Hong Kong stuntwoman Ming Lu, as well as stunt coordinators Chad Stahelski and Hiro Koda, and as a resulted performed nearly all the stunt work herself. In addition to the stellar stunts, realistic graphics, and an often haunting score, the film's actors display a rare chemistry that brings viewers both into their lives and into a possible version of humanity's future."