AllMovie

A 6-year-old girl is kidnapped by a pair of clowns hired to perform at her birthday party shortly after the celebration ends. The girl's dad (Neil Patrick Harris) is a brilliant mathematician who is working on a complex problem and refuses to cooperate with the police, saying that he can get his daughter back without their help. This leads Charlie to believe that the kidnappers are after something that the missing girl's father is working on. Back at home, Alan decides to sell his house.