Sam discovers that his father Raymond has been hanging out with Arkady, much to his displeasure. FBI Special Agent Lisa Rand calls. The quartet known as the the Body Stitchers is back in Los Angeles. Kilbride grudgingly approves the OSP's involvement in the hunt for the group. Sam and Deeks, along with FBI Forensic Psychologist Mark Collins, interrogate Michael Jeffries, who had been contacted by the Body Stitchers. A room with the remains of several people is found. Jeffries says he's just a true-crime aficienado and a fan of the Body Stitchers. Rand and Kensi talk the super into opening Jeffries' apartment. They find a decaying body in an acid-filled tub, thought to be Jeffries' mother. When Jeffries is told, he demands protection from the Body Stitchers. In return, he offers up the location where the group posts the location of their shows on the dark web. Fatima finds their new forum and a  show is about to begin at a 16-theater cineplex. A terrorism warning comes in and Sam get redirected, with Kensi and Deeks staying on the Body Stitchers hunt. Rand locates the correct theater. Someone shoots and the Body Stitchers and audience members flee. Bobby Griffin was shot dead. Kensi captures Cindy Ferguson. Justin Tucker traps himself in an elevator and wants to speak with Vincent. Collins is wounded but sends Deeks after Albert Barrington. The would-be victim says they don't have a photo of the man in charge. Justin leaves the elevator and slits his own throat. Ferguson explains Vincent to Sam. Raymond goes to poker night with Arkady. The autopsy report shows that Jeffries' mother was killed 48 hours before she was found. Collins is Vincent and he helped Barrington escape. Collins shot Griffin. Jeffries has joined them. Sam connects Collins to Vincent.