When an ex-con is mysteriously slain in an alley, Castle and Beckett believe a vigilante is behind the murder. But efforts to identify their suspect are thwarted when they discover that he roams the city in a Superhero costume — and may indeed be a Superhero. Can they capture and unmask the killer before he strikes again?
Gunshots, a fleeing van and a massive blood pool all point to murder, but when Castle & Beckett arrive at the crime scene, they discover that it lacks something – the victim! The investigation leads to the cutting-edge world of life-extension science, a cunning high-tech researcher, and a sleazy porn mogul who invested in a modern-day “fountain of youth.” Meanwhile, Alexis finds out whether she got into Stanford.
The shooting death of a young woman points to Ryan's stolen gun as the murder weapon - the gun stolen earlier by serial killer 3XK. Now Castle and Beckett are up against the clock to track down 3XK before he kills again.
An insurance investigator (Kristin Lehman) assists Castle and Beckett with a homicide case stemming from the theft of a costly sculpture, and a museum benefactor (Jessica Tuck) becomes one of the murder suspects.
Castle & Beckett confront the possibility of paranormal foul play when a world renown ghost hunter is mysteriously murdered while investigating a haunting at a legendary New York mansion.
When Castle and Martha are taken hostage by a crew of bank robbers dressed in hospital scrubs and using classic television doctor names (Trapper John M.D., Dr. Huxtable, Dr. Quinn Medicine Woman and Dr. Doogie Howser), Beckett finds herself on the outside, desperately trying to rescue them — which proves to be even more difficult with a by-the-book hostage negotiator (guest star Dean Norris, “Breaking Bad”) watching her every move. Castle becomes the de facto leader of the hostages, which includes Barry Livingston (“My Three Sons”), and discovers that the robbery is actually a skillfully orchestrated distraction for an even more sinister plan. But with Castle stuck on the inside and Beckett on the outside, will either be able to foil the bank robbers’ plans before it is too late?
Castle, Esposito and Ryan head to Atlantic City to solve the murder of a New Jersey casino owner who was found in an abandoned New York City warehouse. While there, they have a bachelor party for Ryan.
