Callen and Sam work undercover as food truck owners in Mexico to find the source of an anthrax poisoning and prevent a bioterrorism attack.
When Castle is prohibited from working with Beckett or the 12th Precinct he gets his P.I. license and shows up at Beckett's crime scene as a private investigator, where things don't go as planned.moreless
The team investigates when a suicide may not be how it appears. Frost decides to review an old murder case. Angela's new romance isn't a secret anymore.