S5, E17: The team’s latest case takes Brennan back to her alma mater, Burtonsville High School, where she and Booth investigate the discovery of an unidentified skull and upper torso. With Angela’s help, they identify the victim as one of Brennan’s classmates, and notice a possible connection to a second murder committed 15 years prior. Brennan and Booth go undercover as a married couple at her class reunion to interrogate a set of suspects, where even as an adult, Brennan is still predictably misunderstood and her only friend lies in a strangely dark and offbeat janitor (guest star Robert Englund). Meanwhile, Hodgins spills a lab secret.