In The Lives of Others, Castle is holed up in his loft with a broken leg while Beckett & Co. go off to investigate the death of an IRS agent. Cooped up and bored, Castle turns his attention to the building across the street, and believes he witnesses the murder of a young woman.
The episode was doubly significant for the cast, as Stana Katic says, "It's a special episode tonight because [Castle creator] Andrew Marlowe and his wife [Terri Edda Miller] both wrote it. They wrote for the fans who are so sweet and supportive. I think it's going to be a nice glass of champagne for the fans."
Check out a sneak peek from the super-special episode, airing tonight at 10 p.m. on ABC.