When high-school classmates reunite to unearth a time capsule buried 20 years earlier, they find the corpse of an adolescent friend inside; while combing through the victim's life, the team members rehash their own teen years.

Three days before Christmas the body of a bearded man in a tailor-made Santa outfit turns up in a sewer; Brennan visits her father in prison and plots a nontraditional holiday reunion.