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 (guest star William Atherton), and a sleazy porn mogul who invested in a modern-day “fountain of youth.” Meanwhile, Alexis finds out whether she got into Stanford.
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?
In a riveting opening that picks up just moments after last season's climactic finale, Detective Beckett (Stana Katic) fights for her life as Castle (Nathan Fillion), plagued by guilt over his role in the events, struggles to uncover who's behind her brutal shooting. Meanwhile, back at the precinct, Ryan (Seamus Dever) and Esposito (John Huertas) have to adjust, as Victoria "Iron" Gates (Penny Johnson Jerald, "24") becomes the precinct's new uncompromising Captain.