Young adults tackle an escape room. They hear gunfire but can't get out. The gamemaster is shot dead. Jack had recommended McGee takes a vacation and Gibbs suggested The Bahamas. Neither McGee nor Delilah remember how to relax. They make a pact not to talk about the kids or work and find they have nothing else to talk. The dead gamemaster, Norman Mason, was a Naval Reservist. Gibbs finds a hidden room with computers, secret documents, and cash. Mason had worked for a DoD think tank. The victim had a SIM card hidden in his mouth. Mason called The Bahamas on a regular basis so they call McGee to investigate. Delilah wants to go with him. They stake out the phone Mason has been calling. McGee approaches the woman who shows up and she knocks him down and rides away. Delilah found a photo of the getaway moped. The woman at the moped rental stand was a fan of McGee's books and gave him the info for Sienna Michaels. Mason had been investigating the suspicious death of another scientist on the project, Malcolm Lucas. McGee and Delilah discover Lucas with Michaels.  Lucas faked his death to protect his underwater drone, Deep Raven. It was being turned into a weapon. A third scientist, Reynolds, is found dead. McGee and Delilah agree that a murder investigation is the most fun they've had in years. Gibbs finds Fornell's garage has been trashed and there's blood. Kasie figures out that the killer is likely in The Bahamas. Sienna was planning to sell Deep Raven. Delilah finds an airline ticket to D.C. for Sienna. She killed Mason and Reynolds. She shoots Lucas and gets the drop on McGee. They are rescued by Clarence, the hotel server who was Gibbs' old Marine buddy.