A body is found in the park dressed in a Red Riding Hood costume. The victim had been drugged and had recently withdrawn a large amount of money.
A second victim is found dressed in a Snow White costume with the same situation.
A third woman is discovered still alive, in a Sleeping Beauty costume. Detectives search her apartment and find a picture with the three girls in similar costumes and a man. It is discovered that they were high school friends and the man died the night of that picture.
Castle and Beckett speak with the family of the first victim and find out that the victim’s brother in law is the brother to the man from the picture. He admits to trying to blackmail the girls so he could get some sort of payment. The girls had hit the man and left him there to die.
The third woman had killed the other two to try and keep her secret. Castle discovers this when he sees her costume bow is tied incorrectly.
Martha puts on a one woman show at the apartment and invites Beckett to check it out with Castle.