If the job of a sequel is to meet and then exceed expectations, "Freddy vs. Jason" is probably the best sequel of the summer. Like the programmers of the '40s designed to finish off Universal Pictures' "classic horror" phase, "Freddy vs. Jason" pairs up two fading but legendary horror fixtures and then squares them off against each other in the hope that the combined fan bases of each will mean a box office hit. But unlike "Frankenstein Meets the Wolfman" or "House of Dracula," "Freddy vs. Jason" is actually among the best movies in the history of either of the franchises it draws upon. Often knowingly humorous and so unbelievably violent that the mayhem basically answers the question of what a Looney Tunes cartoon would look like if the characters bled, "Freddy vs. Jason" earns every laugh, and works hard for every scream.

Much of the credit goes to a clever script by writers who are smart enough to know that at this point in the long histories of the "Nightmare on Elm Street" and "Friday the 13th" franchises, they are dealing in iconography, and that the essential novelty needed to enliven their work is in getting "Nightmare" villain Freddy Krueger and "Friday" fiend Jason Voorhees believably into each other's company. Their script does just that, then confines all its action to Freddy's Elm Street and Jason's Crystal Lake in the wise belief that one showy central gimmick is enough.

The premise of "Freddy vs. Jason" has a forgotten and extremely weakened Freddy Krueger unable to return to Elm Street from the dark dreamscape he inhabits because none of the children there know he exists ("It's our fear that gives him his power!" explains one of the sitting-duck high school kids early on.) To revive his reputation, Freddy brings Jason Voorhees, the immortal and mute serial killer of Crystal Lake, back from the grave, and sets him loose against the youth of Elm Street. When teens start dying in ridiculously graphic ways, the Elm Street authorities believe Freddy's back in town. As fear of him spreads, Freddy regains his ability to kill the sleeping children of Elm Street. His one remaining problem: Jason, like the sorcerer's apprentice, can be activated, but he can't be turned off, and the two greatest icons of the '80s slasher genre are soon angrily competing for the same limited pool of Elm Street victims.

The movie proceeding from that idea is about as over-the-top as any gore film ever made, and culminates in two lengthy battles between the title villains (one in Freddy's dream world, the other on Jason's home turf at Crystal Lake) that are as well-staged as any fight scenes released in an American movie so far this year.

Under the able direction of legendary Hong Kong action filmmaker Ronny Yu ("The Bride With White Hair"), "Freddy vs. Jason" is a feast for hardcore fans of either character, and likely to bring a new generation of gorehounds into the fold. Think of the film as taking one of those old horror movie double-bills of yore and blending it together into a single 97-minute presentation, with every act of mayhem intact. Can "Abbott and Costello Meet Hellraiser" be far behind? Starring Robert Englund, Monica Kenna and Ken Kirzinger. Directed by Ronny Yu. Written by Damian Shannon and Mark Swift. Produced by Sean S. Cunningham. A New Line release. Horror/Fantasy. Rated R for pervasive strong horror violence/gore, gruesome images, sexuality, drug use and language. Running time: 97 mi