Castle and Beckett investigate the murder of a cruise ship entertainer, only to find themselves trapped at sea with the killer.

Cast: Nathan Fillion, Stana Katic, Susan Sullivan, Jon Huertas, Seamus Dever, Tamala Jones, Molly C. Quinn, Toks Olagundoye, Sunkrish Bala, Mickey Cassidy, Arye Gross, Panuvat Anthony Nanakornpanom, Kristoffer Polaha, Aaron Pont, Katherine Von Till