One clear sign that kids are back in school and that more adults are heading to the movies came last weekend when the steadfastly serious "Agnes of God," in its first week of cross-country release, pulled in more money than the still-strong "Back to the Future." "Agnes of God" made more than $4 million and easily racked up the biggest per-screen averages in the country -- nearly $7,000 per screen as opposed to $2,600 for "Future." But it's too early to assume that the Serious Movie Season is definitely upon us: Another movie beat out those two and everything else -- and it's the kind of movie that brings to mind the Rambo-mania that infected the country early this summer.

Last weekend's champ was "Invasion USA," with Chuck Norris as a patriotic, deadly one-man army out to protect America from its commie foes. The latest in a series of increasingly successful Norris action films, the movie made almost $3 million more than its nearest competitor, giving the ex-karate man his biggest opening ever. Norris might get some stiff competition when Arnold Schwarzenegger's "Commando" opens tomorrow, but for now he's in charge -- and that has to be good news for the folks at Cannon Films. "Invasion USA" is giving Cannon not only one big hit, but also a clear shot at a second: At the beginning of every one of the 1,735 prints of "Invasion USA," Cannon has tacked on a trailer for Charles Bronson's "Death Wish III," which opens Nov. 1 . . .

With the exception of the "Agnes of God" team of Anne Bancroft, Jane Fonda and Meg Tilly, acclaimed actresses had a rough time at the box office last weekend. Sissy Spacek's "Marie," a true-life story, only opened on about 100 screens but fared poorly; Glenn Close's two-role workout "Maxie" was in lots of movie houses but struggled to a dismal $1.1 million; Meryl Streep's "Plenty" dropped 34 percent from the week before. Waiting in the wings is Jessica Lange in the Patsy Cline bio "Sweet Dreams," which opens a limited engagement tomorrow. It has been picking up mixed notices -- including one in which Daily Variety rather bluntly noted, "Lange usually gets lavish reviews (and one Oscar) but has a string of flops except for 'Tootsie,' whose success is usually credited to Dustin Hoffman . . ."

"Bring on the Night," the documentary about rock star Sting and the beginning of his solo career, was shot in only nine days by "Coal Miner's Daughter" director Michael Apted earlier this summer. So it makes sense that postproduction wouldn't take long, either -- and sure enough, "Bring on the Night" is ready to premiere next weekend at Ireland's Cork Film Festival. (Documentaries must be shown at a film festival before Halloween in order to qualify for the Academy Awards.) It'll open across the country Nov. 8 -- at which time, goes the reasoning, Sting's new record should still be hot . . . Meanwhile, the Los Angeles Times has reported two more musicians making movie business inroads: Glenn Frey is moving from the little screen (he was in a "Miami Vice" episode based on one of his songs) to a costarring role in Tri-Star's "Let's Get Harry," in which Frey and Gary Busey head to Mexico to save their brother from terrorists, aided along the way by mercenary Robert Duvall . . . And Michael Jackson reportedly wants to produce a film on the life of flamboyant rocker-turned-preacher Little Richard. When Jackson recently purchased the rights to the Beatles' songs by buying ATV Music, he picked up rights to Little Richard's music as part of the deal . . .

Eddie Murphy has finally, officially, made up his mind. Confirming the word that's been circulating for some time, Paramount Pictures has announced that the first film in Murphy's lucrative, exclusive pact with the studio will be "The Golden Child." Paramount calls it an "exotic action-fantasy-adventure" with lots of special effects. Directing will be Michael Ritchie, whose previous work includes "Fletch," "The Candidate" and "The Bad News Bears." Also on board are producer Edward S. Feldman and executive producer Charles D. Meeker, whose Feldman/Meeker production company is responsible for "Hot Dog . . . The Movie" and a yet-unseen follow-up titled (we should have known) "Hamburger . . . The Motion Picture."