Not as bad as other reviews suggest - in my POV. The riddle does quite some things right even if it's not a complex riddle so to say. (Spoiler: dad survived and kidnapped his boy) Story is fairly realistic and esp in the beginning able to create suspense. I liked the slow pace and overall unagitated feel. Towards the end it drifts more and more into cliches and implausible decisions which take unfortunately some oomph away. Ps: The twisted staircase on the cover has nothing to do with the actual movie.