Rizzoli & Isles Season 6 Episode 15 involves a murder at a "fear club," an event where people sign up to go through a haunted house and get seriously frightened. Some people experience mock kidnappings while others experience mock murders. Unfortunately, one murder turns out to be real.

The detectives' investigation requires Frankie to go undercover at one such event. He is excited about it until Jane mentions spiders. At the event he meets the owner of the club, who pretends to be a murderer with a meat cleaver. The owner can't believe the victim is dead. She was a coworker but he didn't see her that night because she was in a different part of the event. The event is anonymous but he collects email addresses.

One email address is attached to a woman named Karen, who had taken out a restraining order against a guy named Gus Brooks. Karen runs a preschool. She says that Gus was a maintenance guy who used his brother's identity to get the job. When the theft was discovered, he was fired and he kept coming to the school and yelling and scaring the kids. But he went to anger management and is doing well now. Karen refuses protective custody as she runs the school but Frankie puts an officer to work guarding her.

While the detectives are investigating this case, Nina and Vince look into Jane's hacker, frustrating Jane because she is not allowed to have any information about the case. And Vince plans to propose to Kiki; will Maura be able to keep it secret from her?

To find out what happens, watch Rizzoli & Isles Season 6 Episode 15 online.