Castle’s effort to convert Beckett into a lover of Potato Chip Fudge ice cream, his favorite flavor, is interrupted by a cold-blooded murder. Everyone’s favorite frozen confection also comes into play in their case. An ice cream truck driver, Anton Vetotchkin, is found shot dead inside his vehicle. The victim’s parents say he was taking classes for graphic design. His teacher, Natalie Barnes, said Anton got upset during a recent class. All his projects have been deleted from his computer.
The team realizes that one of the children in a local second grade class may have been inside the ice cream truck at the time of the murder. The plan is plant an adult presence inside the elementary school world to get the young witness to come forward. It will have to be someone who 8-year-olds would be able to accept as one of their own. Sounds like a job for a person who is admittedly 90 percent kid. Sounds like a job for Castle.
Castle asks the kids to write a story. It can be fictional or it can be something that happened in real life. He tells the real teacher, Mrs. Ruiz, that he intends to find the facts in the stories to identify the witness. Castle’s first guess doesn’t pan out and leads to an embarrassing scene where the kids mock him for wetting his pants. He didn’t really, but that doesn’t stop the relentless teasing from taking place. “Mr. Castle wet his pants! Mr. Castle wet his pants!” Jason, Castle’s classroom nemesis, snaps a Polaroid picture of the embarrassing incident.
Castle has a private tea party with a student, Emily, during recess. He learns that Emily’s secret is that she’s being bullied by Jason. This isn’t the information Castle was seeking, but it’s a good sign. He’s earning the trust of the kids. He also earns a trip to the principal’s office after Emily uses his advice to give Jason a bloody nose. Castle is forced to cut his teaching career short. While saying goodbye to the class, someone slips him a picture of an ice cream truck. It was drawn by Jason.
The murder victim placed a call to an ex-cop named Clark Jaffe, who was recently killed with the same gun used to murder Anton. The two men were sharing a P.O. Box. Indications are that a man with a Russian accent was coming after Anton, who was desperate to contact a guy named Dmitri Kalenkov, an enforcer for the Russian mob who has also been shot dead. Beckett realizes the killer is after something their victims had.
Jason says he wasn’t in the ice cream truck, but his sister was. She’s a grown-up. They have different dads. She came home after meeting her friend, the ice cream man. Jason’s half-sis is Natalie Barnes, his graphic design teacher. She, Anton and Jaffe were trying to help Russian immigrants who were forced to work in sweatshops get back home by creating passports for them. Anton recognized a bad man from his past in the photo of one of the passports he was making. His name is Polkovnik. He’s a killer. Natalie watched him gun Anton down. Polkovnik is after anyone who has the picture that could ID him.
Polkovnik tosses Natalie’s apartment looking for the photo. He never finds it. That’s because she hid it in a camera case—a Polaroid camera case. Castle says that Jason had brought it in for show and tell. It’s in Mrs. Ruiz’s classroom as they speak. Pokovnik overhears the conversation. He gets into a slugfest with Beckett. Castle gets smacked around as well before dumping a jar of marbles. Polkovnik slips. He’s down for the count just like Castle was when the second graders pulled the same prank on him.
Castle treats the second grade class to cupcakes. Beckett also has a surprise for Mrs. Ruiz. It’s a medal for outstanding service for the NYPD. It’s also a reward for putting up with Castle. In other news, Alexis has been worried about her father. It’s a residual effect of his disappearance. Castle says price of being an adult is realizing that you can’t always protect the people you love. They can still have fun though. Castle orders Alexis to join him on a scooter ride. They’ll go out for pizza. After all, this last case has Castle staying away from ice cream for a spell—even Potato Chip Fudge if you can believe it.