"Serenity" is a movie that shouldn't exist; the fact that it does is miraculous. The film is a continuation of "Firefly," a Fox series created by Joss Whedon, who became something of a pop culture god for his previous series, "Buffy the Vampire Slayer," and its spinoff, "Angel." "Firefly" was a science fiction series set hundreds of years in the future, and at times it resembled a Western more than it did a typical sci-fi show. After using up the Earth, humanity sought out a new solar system to call home; there they colonized moons and inner planets through terraforming. The core worlds saw prosperity and considered themselves civilized. The outer colonies, on the other hand, resembled the American frontier both in their poverty and lawlessness.

The series centered on Malcolm "Mal" Reynolds (Nathan Fillion), a roguish captain of a Firefly-class transport vessel called Serenity. Fueled by a desire for independence, Mal fought against the unification of all the colonies by the central government, the Alliance. He failed, and named his ship after the climactic battle of the war. With one of his surviving war buddies as his second-in-command (Gina Torres), a pilot (Alan Tudyk), a mechanic and a simple-minded strongman (Adam Baldwin), he started a transport business of both the legal and the other kind. At the start of the series, a young doctor (Sean Maher), his schizophrenic sister (Summer Glau) and an enigmatic preacher (Ron Glass) joined the crew. Whedon's strength is in his dialogue and characters, and coupled with a perfect cast, the show was a rarity of near-perfection on television.

"Firefly" wasn't much of a success when it aired and was eventually cancelled after only 11 episodes-and the fans blamed its failure on Fox. By showing the series episodes out of order, not beginning with the pilot Whedon intended and mucking up the time slot of the series, Fox killed the show. Despite the mishandling of the series, "Firefly" gained a cult following that stayed loyal until the DVD release a year later. Then things got really interesting.

The "Firefly" DVD ended up being one of the best selling items ever on Amazon and helped introduce the show to millions of new fans. As the fanbase grew, Universal saw an opportunity at hand. Eventually, it signed a deal with Whedon to make a film based on the series and "Serenity" was born.

The film is a direct follow-up to the events in the "Firefly" series, but it also has newcomers in mind. While the background information of "Firefly" is certainly helpful, it isn't entirely necessary to enjoy the film. The plot concerns the ship's resident psychic and schizophrenic, River, who is being pursued by the Alliance. The Alliance believes that River knows something dangerous to the government's reputation and assigns a high-level assassin to the task of finding her.

Whedon makes memorable villains, and this operative, played by Chiwetel Ejiofor, is no exception. In true kung-fu/Western/samurai film fashion, he is a nameless warrior defined only by his ability. Ejiofor takes to the character naturally and crafts a deliciously evil villain who haunts the crew throughout the film.

The unique patois that made up the dialogue of the series returns in full force once again. Lines like, "Been more'n a year since I had anything twixt my nethers didn't run on batteries!" are commonplace and help to cement the film's universe. "Serenity" rewards repeat viewings because of the meticulous attention paid to dialogue; it's almost impossible to get everything on the first viewing. The film also keeps with "Firefly's" penchant for interspersed Chinese within the dialogue, although it has been noticeably watered down. When humanity left Earth, the U.S. and China were the only remaining superpowers, and the series tried to show this by throwing in Chinese dialogue once in a while.

Taken as a whole, "Serenity" feels as if it were an entire television season's worth of plot crammed into two hours. As mentioned before, the plot is fairly easy to follow, but it may be difficult for newcomers to understand the characters' motivations and actions. The film tries its best to be accessible to non-fans, but ultimately it may prove too confusing for them. Fans of "Firefly" have already spent 14 episodes with these characters, and the film may rely slightly too much on that background knowledge. This is not to say that viewers coming in without any previous "Firefly" knowledge won't enjoy the film, but they will certainly be seeing a different film from the fans.

For "Firefly" fans, "Serenity" is everything you would ever want in a "Firefly" film. For everyone else, it is an exceedingly satisfying sci-fi/action film, and a perfect gateway into the "Firefly" 'verse.