Castle and Beckett celebrate this closed case on the disco dance floor. The whole team shows up to cut a rug, even Captain Gates. Watch this groovy scene from Castle Episode 620: That '70s Show.
Beckett and Castle get into costume when they try to solve a three decade-old Mafia hit by interviewing a witness who thinks it's still the 1970s. "Castle" airs Mondays at 10 p.m. ET/PT on ABC.