In the future, we've abandoned Earth for another solar system: after a war, the inner planets are controlled almost to the point of fascism by the Alliance; the outer ones remain a free frontier, like the Wild West. River (Glau), a telepath with expert combat skills, fabricated by the Alliance, is rescued by her brother (Maher) and the two end up on a ship run by former soldier Malcolm Reynolds (Fillion) and his crew. But her former owners put the Operative (Ejiofor), a relentless hunter, on their trail even out into the zone of the solar system where the cannibalist Reavers hold sway. Decoding the secret held inside what remains of River's mind might be their key to survival - or might put them in even greater peril.
It's a nicely grubby view of the future: spaceships barely work and humanity is its own biggest threat, not "aliens". However, I found it tough to get involved in the characters, Whedon's dialogue seeming very artificial + contrived. [The style works better in Buffy, where the supernatural stuff signalled a certain unreality. This seems to pride itself on gritty plausibility]. Or perhaps it's that the specific reason why they're being hunted so relentlessly, is hidden until 80 minutes in. It does make sense, and the climax is a lot more engaging, as it's clear what's at stake and why the struggle is worthwhile. Despite this grandstand finish, overall, this seems like a wholly satisfactory TV show (think Blake's 7, with much worse acting and better FX), but is largely disappointing cinema.