Five 20-something pals take off for a weekend retreat, where they are set on by murdering zombies. Producer Joss Whedon (who co-wrote with director Drew Goddard) has built a career on making silk purses out of sow’s ears, but sometimes a pig’s ear is just a pig’s ear. Here the hog gristle in question is the same dumbass slasher-movie hokum as last year’s Shark Night 3D, with cliché characters walking around marked “Kill me first” and “Kill me next.” Press materials warn reviewers against disclosing the movie’s “secrets,” but anyone with an IQ larger than their shoe size will see it all coming an hour ahead of time. Whedon is on probation now; he’d better be extra-good from here on out. Chris Hemsworth, Kristen Connolly, Richard Jenkins, Sigourney Weaver and others struggle to make this turkey fly. .