Castle - Season 4 Apr 2026

Season 4 is widely regarded by fans as a peak for the "Caskett" relationship, focusing on themes of healing and change.

During the investigation, they recall visiting the morgue to see Lanie, who found a . Castle notices a postal barcode on the back of the paper, which becomes the key piece of evidence used to track where the document was sent from and eventually lead them to the culprits. Key Highlights of Season 4 Castle - Season 4

: The season features a notable appearance by Meghan Markle in the episode "Once Upon a Crime," where she plays a serial killer who dresses victims as fairy tale characters. Season 4 is widely regarded by fans as