Director and co-writer Brad Anderson has crafted a Hitchcockian nailbiter about the mystery of human intentions set on an old-fashioned train speeding across the Siberian wilderness. Emily Mortimer stars as Jessie, an American woman traveling with her hayseed husband Roy (Woody Harrelson) from Beijing to Moscow. Along the way, they share a compartment with another young couple, Carlos (Eduardo Noriega) and Abby (raccoon-eyed Kate Mara), who may have something to hide. Anderson may be a little too reliant on blatant misdirection to build suspense, but he does know how to tighten the screws on his characters, raising the stakes as the film moves methodically toward its climax. The best thing in the film is Mortimer’s terrific performance in a rare leading role — the director deserves lots of credit for singling out her winning combination of smarts, soulfulness and, as the film wears on, desperation. Harrelson is even more gentle and relaxed than usual, and Noriega smolders amiably in his role as the charming stranger. Some of the photography is lovely, although Lithuania stands in for the forested Russian landscape. The third act is a bit of a let-down, but otherwise this is tense and absorbing filmmaking. B