It starts really well and has a great opening half hour. The first scene is fantastically done and chilling, and sets a great atmosphere going forward. After that I feel like it doesn't really build on the premise or the momentum it promises with its excellent concept, but it's still a decent watch. Jason Segel gives a good performance though I didn't really buy his chemistry with Rooney Mara. She certainly had more to do here than in Lion though. B-