10/21/2014 01:19 pm ET Updated Dec 06, 2017

Castle's Childish Ways Help Solve A Murder In 'Child's Play'

Nicole Wilder via Getty Images

Castle finally gets to use his inner child to help solve a case.

In “Child’s Play,” the fourth episode of the seventh season of “Castle,” the mystery writer’s childlike tendencies finally come in handy when having to deal with a lively class of second graders.

When a young man is found murdered inside an ice cream truck Ryan quickly finds out he is Anton, son of the Russian immigrants who own the vehicle. As it turns out there is a witness to the murder, someone was hiding in the storage cabinet when Anton was killed. The only clue is a left-behind permission slip suggesting it was a second grader from Mrs. Ruiz’s class. The problem is that none of the kids come forward when asked about the incident.

So Castle’s antics in the classroom begin, since he is “90 percent kid” himself Kate agrees he is the best man-child for the job.

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Castle is pretty confident that his perfect plan to find the witness will work but the second graders provide more of a challenge than he expected. As soon as he walks into the classroom he gets an eraser to the face and things just get more complicated from there.

He asks the kids to write any story they want but this plan just gives him a false, though ultimately hilarious, lead. Then Castle thinks he found his witness when Emily, another student, says she has something to tell him. Castle and Emily dress up beautifully as princesses and settle into a tea party when Emily confides that she is being bullied by fellow classmate and troublemaker Jason.

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Castle’s advice to Emily gets Jason a punch in the face and Castle is asked to leave. But on his way out he finds a picture of an ice cream truck in his pocket. One of the students is trying to tell him something. A little bit of sleuthing reveals the artist to be Jason, the one student who Castle doesn’t get along with. After some smooth talking from Beckett Jason reveals he wasn’t in the truck, his half-sister Natalie Barnes was.

Natalie was Anton’s graphic design teacher. She revealed she was working with Anton, his childhood friend Dimitri and a former police officer named Carl Jaffe, all who were found dead, to help create fake passports for Russian immigrants who’d been brought to the U.S. under false pretenses and were unable to get back home.

This work eventually led Anton to recognize a photo of a war criminal from Russia who is killing anyone who can identify him and looking everywhere for the photo. Castle and Beckett fight the criminal in the classroom where eventually Castle is able to knock him down with a jar of marbles, but not before the killer delivers some blows himself.

“Child’s Play” is another fun Castle episode. The story is kept light and there is still no mention of Castle’s disappearance except for Alexis’ strange smother-mothering of Castle, which is kind of creepy and gets the audience to remember that she was once kidnapped as well. Sure, Castle enjoys being waited on hand and foot in the beginning but he then acknowledges what Kate has been saying all along, it’s odd. He talks with Alexis and she promises to back off.

Worth Noting:
-Second-grader Emily being protective of Castle and interrogating him and Kate about their wedding is adorable.
-A big thank you to Nathan Fillion for another fun-filled live tweet of the episode.
-Who doesn’t want to try potato chip fudge ice cream?
-Everything about Castle’s interaction with a bunch of 8-year-olds was hilarious, from “wetting his pants” to making faces at Jason and being scolded by Mrs. Ruiz.
-Mrs. Ruiz gets a medal from the NYPD, since she put up with Castle for two whole days.

Quote of the week:

Beckett on Castle's time with the second graders:

"He's 8-years-old. You've been here for a day and a half and you already have a nemesis?"

"Castle" airs on Mondays at 10:00 p.m. EDT on ABC.