The BAU investigates a serial rapist who had been attacking young women at religious schools and stopped for six weeks.
The 126 crew responds to a military tank on the loose in downtown Austin and a human pile-up at the roller derby. Meanwhile, new paramedic captain, Tommy Vega, joins the team and Owen is reunited with his ex-wife and T.K.’s mother, Gwyneth, and receives an update on his cancer.
After a volcanic eruption wreaks havoc in Austin, the members of the 126 race to save lives at a college pool party, a family’s mini-golf outing and a woman trapped in her food truck by a horde of scorpions.
When a woman is found dead in her car, the investigation leads to New York Mayor Robert Weldon (Derek Webster), one of Castle's longtime friends.
Lynette tries to talk her mother out of marrying an obnoxious man; Bree runs into Keith's ex-girlfriend and makes a shocking discovery about his past; Carlos starts to worry about Gaby's obsession.
