At the same time, Shyamalan undercuts his considerable talents by aiming for Significance. What come across at first like playful structural fillips turn out to be attempts at giving the film religious dimension. The utterly tone-deaf emotional climax had me leaving the theater in a bad mood. "Yeah," I snarled, "that was like a movie Steven Spielberg might make - if he made movies that were incredibly slow and fraught with tedious spiritual baggage."

OK, that's a little unfair, because the movie is pretty entertaining and certainly moves more quickly than either of its predecessors. Signs' best asset is its sense of humor. Shyamalan's willingness to cop to hokey, secondhand storytelling is a goodwill gesture that lowers the resistance of an audience to some very effective scare tactics. One scene in particular, depicting the broadcast of video footage taken at a children's party in Brazil, is unspeakably creepy, and Shyamalan makes the most of the opportunity to photograph scenes that take place in a cornfield at night. Most surprising may be that he tips his cards early on-it can't be more than a half-hour into the film before he springs an image that reveals where all this is heading. After two films that relied on obfuscation to build their narrative web, Signs is refreshingly direct.

Shyamalan's affinity for supernatural themes is one of the reasons he's being touted as a populist filmmaker and this generation's answer to Spielberg. The serious-as-death-itself The Sixth Sense followed directly on a wave of films that increasingly treated the horror genre as yesterday's news, a subject ripe for satire and mockery. Shyamalan understood, however, that one of the reasons people go to movies is to be scared - to get the feeling that they're confronting the unknown without leaving the comfort of a movie-theater seat at the local shopping mall. The Sixth Sense's old-school style - lots of master shots, relatively few edits - was actually an asset in that it contrasted spookily with everything else that was in American movie theaters, and the twist ending sealed the deal.

Among the cues Shyamalan takes from Spielberg are his focus on the set dressing of real life as props for science fiction. Here, a discarded baby monitor becomes a device for listening in on otherworldly transmissions, and the snippets of live TV broadcasts from around the world become outright chilling. Is there any way to hear little Sarah's complaint that all the TV channels are suddenly showing the same program without thinking of the saturation coverage that followed the World Trade Center disaster?

If he's a little more morbid that Spielberg, who famously insisted that alien visitors would be our friends, then he's also firm in his belief in the human spirit. In the two films where humans are given special powers, they use it to try and help make the world right again - fingering the killer of an innocent little girl or foiling would-be murderers. In all three cases, Shyamalan is interested in the idea of justice, and in both Unbreakable and Signs, justice is meted out in brutal fashion. Unbreakable's action climax came when Bruce Willis, finally willing to try out his superhero gig, pounded the living shit out of a would-be murderer in a scene of intense physicality. That Shyamalan shot much of it without edits, surveillance-camera style, only added to the feeling of vigilante unease. That a similar level of physical violence in Signs is dealt out to an alien intruder certainly makes it easier to take. But it's still a little off-putting.

In terms of its subject matter, Signs is mainly science fiction. But because of its style (Shyamalan wants to go "Boo!" as often as possible) and since it's eventually revealed to be, basically, a monster movie, I think of it as horror. Indeed, it borrows liberally from SF-horror classic The War of the Worlds and strongly echoes such straight-up horror films as Prince of Darkness and Night of the Living Dead - even The Blair Witch Project. But the final reel is closer in mood to that of a film that's not thought of as horror at all - Sam Peckinpah's Straw Dogs, in which Dustin Hoffman is driven to brutal violence by the violation of his wife and home. Signs isn't as unforgivingly focused as that film. Still, it is driven by the personal (if not vengeful) demons of Graham Hess (Mel Gibson), a man who has lost a wife and is driven nearly insane at the thought of losing his children. Fortunately for him, brother Merrill (Joaquin Phoenix) still lives at home and helps keep the blood off his hands.

"Vengeance is mine," sayeth whom? Where Shyamalan stumbles, badly, is in trying to incorporate a philosophical idea having to do with faith and the nature of coincidence. Apparently not content with simply making a boffo horror picture, Shyamalan tries out the tactic of using ham-fisted coincidences throughout the film in order to build, Thomas Aquinas-style, an a posteriori proof of the existence of God. For instance, there's an early scene in which the perpetually sleepy-looking Rory Culkin is seen popping an inhaler into his mouth, and you can bet that before the end of the film that kid is going to be locked up somewhere where he can't get to his asthma medicine. What's more, that asthma is going to help save his life. Elsewhere, Shyamalan jerks maximum tears from a flashback involving Hess's wife in an incredibly gruesome situation, then makes glib use of that scene at the film's conclusion. At the end of Signs, the eldest Hess, who had earlier all but renounced his faith, dons the white collar once again. Having witnessed the various wild coincidences written into Shyamalan's script, one of which saves his little boy's life, he deduces that God must in fact exist. Coming at the end of an alien-invasion potboiler, this brand of po-faced righteousness is awfully hard to take.

In Shyamalan's world, it's children who will lead you to a state of grace. In one scene, young Morgan declares "I hate you" when his father refuses to say grace at the dinner table; by the end of the scene, the two are embracing tearfully - a metaphor, one suspects, for Hess's relationship with the Lord. Is the joke on Hess for buying Shyamalan's claptrap hook, line and sinker? If you're willing to stretch, you could describe Signs as an exceedingly bleak and ironic look at the irrationality of faith. More likely, it's a movie made by a man who wants desperately to believe everything will work out in the end. In that, he does God no favors - it's awfully chilly comfort to see the contortions he goes through to win his happy ending.