When a permission slip is found in the storage area of an ice cream truck in which the driver was murdered, Beckett and Castle realize that a 2nd grade student may have witnessed the killing. When none of the children are willing to come forward, Castle goes undercover in the classroom to see if he can get them to open up.

Rick gets the kids to write their own stories, plays Army men, and dresses up in fairy wings and a tiara for a tea party but fails to figure out who the witness is until Jason, the class bully puts a picture of an ice cream truck in his pocket. After some prodding, Jason admits that his adult sister was in the truck but told Jason not to tell anyone.

Turns out the sister, Natalie was dating the victim and the two, along with a retired cop where helping Russian immigrants obtain fake papers to get back home. The scheme unearthed a Georgian war criminal who was willing to kill to get his passport photo back. Castle ends up using tricks from his 2nd grade class to help Beckett catch the killer. Watch Castle Season 7 Episode 4 online here at TV fanatic.