Genre dissections like The Cabin in the Woods are risky ventures. When filmmakers are clearly intent on both telling a story and offering a self-reflexive statement, there’s a significant chance that one impulse could overwhelm the other. The possible results — an ineffectual drama or a suffocating, pretentious satire — are not pleasant. So it’s fortunate that Cabin director/co-writer Drew Goddard, working closely with producer/fellow writer Joss Whedon, manages the tricky balancing act. His long-awaited horror movie, which has sat on the shelf for more than two years thanks to upheaval at original distributor MGM, is smart and fun, packing unexpected surprises while cleverly recalibrating genre expectations. The film’s about a group of five archetypal college friends — among them the jock figure (Chris Hemsworth), the stoner (Fran Kranz) and the “virgin” (Kristen Connolly) — who head to an isolated cabin for the proverbial weekend getaway. Naturally, something goes terribly wrong while they’re there, but it’s surely not what you think.