Having never watched Firefly – Joss Whedon’s short-lived Old West-meets-Star Trek TV series – I’m in no position to make comparisons between it and Whedon’s cinematic spin-off Serenity. On its own, however, this satisfying science-fiction saga has enough richly drawn characters and clever writing to make up for the inescapable impression that it’s a condensed version of a more expansive work. In the 26th-century, man has colonized much of the cosmos and an intergalactic civil war has left the malevolent Alliance in power, though there’s still room in the universe for Mal (Nathan Fillion) and his motley crew of renegades, who fly from planet to planet in the titular bucket of bolts doing odd jobs both legal and illegal. When they agree to transport a schizophrenic psychic named River (Summer Glau), the Serenity crew finds itself hunted by eloquent Alliance assassin The Operative (Chiwetel Ejiofor), though the film’s real joys come less from the familiar dogfights and kung-fu brawls – a gorgeously iconic battle-pose image of Summer notwithstanding – than from Whedon’s assured vision of a rough-and-tumble future and Fillion and company’s wry, self-deprecating rapport. The first half has a simultaneously sprawling yet intimate quality; the latter portion, unfortunately, is too busy by half, and its attempts at allegorical depth are undone by a climactic revelation that, upon close scrutiny, makes little logical sense.