When the body of a marine is found after a party in an illegal night club, the team investigates a number of possible leads - including blackmail and accidental death.
When a web celebrity is murdered, Castle and Beckett explore the flashy world of internet fame. But when the killer posts pictures from the crime scene on a photo-sharing site, they realize they are up against a social media sociopath who may strike again.
With Josh's life on the line, Eve traverses the dangerous wilderness back to the clearing to save him. Desperate to kickstart a rescue mission, Gavin and Izzy work to prove there are survivors alive inside the sinkhole as government agents track their every move.
A power play ensues between Jack and "The Others" as Juliet's future hangs in the balance. Meanwhile, Kate, Sawyer and Karl continue on their journey away from "Alcatraz."
Bob goes undercover as a teacher after children of government officials and foreign nationals are taken hostage, and Lissy's crush on a boy at school leads to big trouble.
