There are times (and plenty of them) when Slither slops over from smart, affectionate homage into unmodulated frat goofiness as Gunn cannibalizes so many horror plots with such high spirits.

Though it occasionally dips too deep into a well of redneck humor, Slither cleverly exploits the nervous laughter that fills a theater whenever a horror movie gets too frightening to bear.

Slither begins briskly, gradually accelerates and eventually achieves a breakneck momentum that makes the wild ride even more exhilarating.

It's the kind of movie that used to be called "trashy good fun," only there's nothing trashy about it: Gunn, who scripted the 2004 "Dawn of the Dead" remake, is clearly punch-drunk with horror-movie love; Slither is, among other things, a freewheeling homage to "The Blob, Invasion of the Body Snatchers" and just about everything by George Romero.

Aside from Henry, Gunn's cast is on a collective wavelength. Banks, whose perkiness carries a slightly demented edge, matches up well with Nathan Fillion, who plays the lovelorn police chief.