SCREAM screenwriter Kevin Williamson takes a step back and writes the kind of movie SCREAM mocks. You can see him now, soaking up videos of FRIDAY THE 13TH and HALLOWEEN -- not to mention the lesser likes of HE KNOWS YOU'RE ALONE, TERROR TRAIN and MY BLOODY VALENTINE -- and saying, "I can do that!" And he can. Bright, graduating high-school seniors Julie (Jennifer Love Hewitt), Helen (Sarah Michelle Gellar), Ray (Freddie Prinze Jr.) and Barry (Ryan Phillippe) accidentally run a man down on a deserted road and, in a panic, decide to get rid of the body and pretend it never happened. A year later, the letter arrives: "I know what you did last summer." Someone is stalking them, armed with a deadly gaffing hook: Can they find the slasher before he -- or is it she? -- finds each and every one of them? Once you're over the vertiginous feeling of early '80s deja vu, Williamson's script -- which contains flashes of SCREAM's wit and clever self-referentiality -- clicks along nicely under the guidance of first-time feature director Jim Gillespie. The youngsters all turn in game performances, but the standout is Anne Heche, whose weird Missy Egan is pure Mimsy Farmer at maximum twitch. If you like this sort of thing, you've seen it all before. But if you're under the age of 20, you've probably never seen it on a big screen in a first-run theater.