With tensions rising between Castle and Beckett, Castle finds himself a new partner -- Detective Ethan Slaughter, a tough and colorful cop from the city's gang unit. But Castle gets more than he bargained for when Slaughter shows him a grittier side of police work that puts Castle in the line of fire like never before.
Elenco: Nathan Fillion , Stana Katic , Susan Sullivan , Seamus Dever , Jon Huertas , Molly C. Quinn , Tamala Jones , Toks Olagundoye , Seamus Dever , Susan Sullivan , Tamala Jones .