An earthquake derails a DC subway train and a partially skeletonized body emerges out of the overflow. Sweets, who was on the train, deals with the post-traumatic stress of surviving the accident while a young man he talks to on the train dies next to him. 

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. 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. Meanwhile, Hodgins spills a lab secret.