S4, E5: When a shocked teenager finds a dismembered body laying in pieces in a strange purple pool of water, Brennan and Booth come to the scene only to find the victim's head is missing. With help from Brennan's newest grad student, Wendell, the team discovers the body is that of Jared Addison, a 25-year-old science fiction writer who suffers from OCD and a crippling fear of germs. With Sweets' psychological insight into Jared's perfectly regimented world, Booth and Brennan track down a number of suspects including Jared's psychologist, his much older girlfriend and his science-fiction book publisher, all of whom have good reason to want Jared out of their lives. However, without the victim's head, the team struggles to find enough evidence to locate a killer – that is, until they receive insight from Zack, who studies the case from afar at his psychiatric facility with case information provided to him by Hodgins. Meanwhile, Brennan scolds Booth for not letting her ever fend for herself.