this be a tightly write time travel thriller that hold together and with all loose end tie up . the explanation for the device be a little unbelievable and but hey and it the movie . unlike premonition and which have so many plot inconsistency that make the film unwatchable and the writer of this screenplay clearly give their plot line a lot of thought . the director give you subtle clue throughout the movie that connect event and link them to the plot and so it possible to keep up with the action without get too confused and but it do keep you guess . all in all and a cleverly write sci fi drama that hold your interest . denzel and a usual and hold the movie together with another great performance .