Interesting premise, nice atmospheric production, but there are too many gaps in logic & in the end the story doesn't come together very convincingly.

Also ... I hate to say this, but I found Sandra Bullock's face, which is in a LOT of close up scenes, disturbingly "plasticky". Bullock is 54, not 30, and the work she has had done on her face ends up making her look odd - like so many aging movie stars. I guess it's a catch 22: stars, especially (but not only) women, need to "look young" to get parts, but having plastic surgery takes away from their faces the lines & marks of aging that give their faces character & allow them to be expressive.