The plot isn't all that believable, but it wasn't supposed to be. Diaz's character goes through some development making it fun to see her change from total naive ditsy to self-confident and purposeful (but perhaps the rapid development was part of what was not so believable). Cruise was as charming as ever as an actor: his action sequences (again totally lacking in reality) are great fun to watch. I went by myself, because I thought it was going to be something my wife would not enjoy. Regretted that. She would have really enjoyed the development in the relationship between Ron and June (perhaps a bit of a chick flick in that respect). I still puzzle over the title. Not sure if "Knight" is supposed to represent Cruise as a Knight in signing armour. I think "Day" has something to do with the theme of "Someday" that brackets the story line. Definitely entertaining!!! and if that's what you want, go see Knight and Day.