Beckett works on her hardest case yet as she waits at the scene of Castle's accident and finds out details about the car crash.
The team take a look at the murder of a toy company CEO and Castle uncovers a lead to his mysterious disappearance which sees him becoming involved in a dangerous investigation of his own.
After a pool shark is killed by an unseen force, Castle and Becket discover evidence that the killer could have paranormal powers. Castle and Beckett try to get their lives back to normal following his disappearance.
An ice-cream vendor is shot and an unidentified schoolchild could be able to help with the case. Castle attempts to find the child by working undercover at an elementary school.
After Castle and Beckett investigate an Internet star's murder, they discover some photos of the crime posted online by the killer.
Castle finds himself in an alternate universe where he's never met Kate Beckett as he investigates a murder. Castle has to convince Kate, Esposito and Ryan to allow him to help in their investigation so he can find his way back home.
Castle and Beckett pretend to be newlyweds at an Old West resort as they attempt to find out more about a possible poisoning homicide.
Esposito finds himself amongst some subway passengers who are taken hostage by a mysterious gunman.
Some older action heroes attempt to help Castle and Beckett investigate an actor's murder.
Castle and Beckett learn that an ER doctor who was shot in the street was a mob doctor.