This article features a mathematical game called "Mystery Person." The author describes how the Mystery Person game was tried with first-graders [age 6]. The Mystery games involve the generation of key questions, the coordination of information--often very complex information--and the formulation of consequences based on this coordination. Children are deriving information, not merely receiving and storing and practicing facts, rules, and procedures as is so common in school mathematics. The author stresses that there is one more aspect of the mystery games aside from children's eagerness, success, and satisfaction in solving mysteries, all non-trivial issues, and that is that the games involve generating new knowledge from old with logical certainty. This activity, inference, is at the heart of being human.