PULPY AND DUMB, Shutter Island takes place in what US Marshal Teddy Daniels (Leonardo DiCaprio) refers to as "a mennal 'ospital for da criminally insane," and a fine mennal 'ospital it is: Full of leaky ceilings, pitch-black hallways, and flickering lights, Ashecliffe Hospital makes the joint in One Flew over the Cuckoo's Nest look like a Chuck E. Cheese.

It's 1954, and Daniels arrives at Ashecliffe—which, naturally, is located on Boston Harbor's remote, gloomy Shutter Island—with his new partner Chuck Aule (Mark Ruffalo) to investigate a mysterious disappearance. If the pounding, melodramatic score wasn't enough of a clue that something isn't right, Daniels and Aule soon meet eeevil shrink Dr. Cawley (Ben Kingsley), whose duties at Ashecliffe are apparently split between treating patients and lurking around being all weird and sinister. Oh, and, Daniels keeps having surreal dreams about his dead wife (Michelle Williams)—not to mention gruesome flashbacks to Dachau, which he helped liberate during WWII.

Shutter Island is the sort of movie where supposedly smart characters do idiotic things; where lightning dramatically flashes to underscore plot developments; where things lunge from shadows not because it makes sense for them to do so but because... well, lunging is just what things in shadows do. Director Martin Scorsese (working from a screenplay by Laeta Kalogridis, who in turn is working from a book by author Dennis Lehane, he of the maudlin Mystic River and Gone Baby Gone) seems eager to try out some time-honored genre clichés: In a vicious storm, there's a winking self-awareness as Daniels and Aule tromp through a cemetery before taking shelter in a crypt; later, Daniels stoically observes a swarming army of filthy rats. The music jolts, character actors offer dire warnings, and for its first hour or so, Shutter Island is, if not scary, satisfyingly creepy.

I won't spoil how Shutter Island ends, but suffice to say there's a shot of DiCaprio screaming "NOOOOOOOOOOOOOOOO!" at the heavens, and also that the climax would be considered pretty shoddy even by M. Night Shyamalan's standards. It's not like everything in Shutter Island goes to shit all at once—it's more of a gradual progression, with things sloooowwly getting sillier and sillier until one looks up and realizes they're in the sort of movie where Leonardo DiCaprio is shouting "NOOOOOOOOOOOOOOOO!" and some jackass in the theater is muttering "Pfft. Knew it." It's hard not to picture Scorsese when this happens, his caterpillar eyebrows raised in surprise: "I was just trying to make a pulpy thriller!" you can almost hear him saying over the end credits. "And then before I knew it, Leo was shoutin' at the sky and... goddammit."