Fox Broadcasting Co.'s blunder three years ago with a little-seen TV program called "Firefly" is the big screen's gain today.

It's also a big gain for Joss Whedon, writer-director of the rousing "Serenity," which is based on "Firefly." Whedon, screenwriter of "Toy Story" and creator of "Buffy the Vampire Slayer," brought his original "Firefly" — a promising science-fiction TV series — to Fox in 2002. Impatient network executives undercut "Firefly" by rejecting Whedon's slow-building, two-hour pilot (which carefully introduced major characters, background, etc.). Instead, Fox launched into episodes that left viewers tantalized but without bearings.

"Firefly," no surprise, was yanked after 11 weeks. A DVD set has gained enthusiasts, but Whedon himself — currently committed to write and direct the long-awaited "Wonder Woman" feature — decided to rework "Firefly" into his filmmaking debut.

The result is "Serenity," a boisterous, semi-comic action thriller that more closely resembles a condensed season of a television drama than a three-act feature. But it is enriched by Whedon's typically bracing yet sensitive dialogue and appealing, misfit characters.

Movie review

Showtimes and trailer

"Serenity," with Nathan Fillion, Adam Baldwin, Gina Torres, Summer Glau, Sean Maher. Written and directed by Joss Whedon. Rated PG-13 for intense violence and action, and some sexual references. 119 minutes. Several theaters.

Leading the film's picaresque adventure, set 500 years from now, is Mal Reynolds (Nathan Fillion), captain of a small, battered space vessel called Serenity. A renegade who fought in a losing war for independence against a heavy-handed, interplanetary government, Mal now keeps out of sight, a freelance transporter on the galaxy's rim.

There, he and his crew visit settings akin to classic Westerns, where unforgiving terrain is tough on settlers, where savagery erupts and where codes of honor, such as Mal's, are a bulwark against chaos. One of the delights of "Serenity" is the astonishing sight of Mal's weapon of choice: a six-shooter of the sort that routinely flattened bad guys in countless Western serials. (Mal's lightning-fast draw is something to behold, too.)

Equally incongruous yet stirring is "Serenity's" language, which at times (particularly in scenes between Mal and his second-in-command, played by Gina Torres) sounds like a tough-but-elegant hybrid of frontier America, 19th-century seafaring and futuristic, starship jargon. Fillion, who at first blush does not look the part of a two-fisted paladin, is moving whenever he communicates emotion — admiration, undying loyalty — while outwardly speaking about the condition of his ship.

"Serenity" follows a crucial story thread that Fox mangled. Against the wishes of the ship's most battle-hardened mercenary (a very funny Adam Baldwin), Mal takes a pair of fugitives aboard. They include a psychic named River (Summer Glau), a victim of painful experimentation by the government, and her doctor brother, Simon (Sean Maher), who has rescued her.

Mal's help proves fortuitous. Not only could Serenity use a physician, but River turns out to be the latest of Whedon's willowy female warriors, capable of slaying crowds of fearsome, cannibalistic degenerates called reavers.

"Serenity's" only serious failing is that it doesn't move or look like a film so much as it feels like a lot of television scripts fell into a compactor.

Whether this structural problem suggests feature films might be Whedon's Achilles heel or if he just had specific difficulty getting "Firefly" to transition into "Serenity" remains to be seen. Either way, getting hung up about it while watching this enjoyable film would be a mistake.

Tom Keogh: tomwkeogh@yahoo.com