Josh Hartnett is the likable local lawman in an Alaskan town where it gets dark for 30 straight days each winter, and, this winter, a squadron of vampires is moving in. “We should have done this ages ago,” says their leader (the immortally reliable Danny Huston), no doubt echoing whichever movie-studio executive had Steve Niles and Ben Templesmith’s graphic novel summarized for him and knew a good concept when he heard it. Speaking of which, all the ads keep saying, “Based on the graphic novel,” but without naming Niles or Templesmith, and it’s hard to know whether that’s a lure or an apology. Anyway, director David Slade has fun pacing the progressively gorier action among his dimly lit snowscapes; Huston relishes tormenting his victims with Nietzschean pronouncements of God’s unavailability; and our hero, bless his Hartnettism, turns on the acting turbo boost to attempt some real emotional resonance. Not bad, but let’s just say the movie could have used a tad more intentional humor.