The concept of making the audience wonder whether the hero is really being threatened or is the victim of delusions, has been used several times recently. I enjoyed this take on it better than most and I love Patrick Stewart in any role! I hadn't expected it to be so heart-wrenching at times, but it was. One scene, in which Mace (P.S.)is doing a cognitive test for his doctor, was particularly effective. As a result, this was not only a suspense movie it had some very realistic portrayals of the slow but steady mental decline of Alzheimer's victims--and how tragic that is, as they realize it is happening. I think I appreciated that accurate and informational aspect as much as I did the mystery of Mace's activities with his complex computer set-up. I watched this while walking on my treadmill and usually do a movie in two sessions. This one kept me going through the entire time.