Last week on "Castle," Rick assured Kate that he still had hope in their marriage and she clearly does too, suggesting plans for their second wedding anniversary in Monday night's episode.

Beckett's (Stana Katic) latest investigation lands her on a cruise boat and Castle (Nathan Fillion) also ends up onboard, to his wife's chagrin. When he brings up the idea of buying a boat, Beckett considers it for their second anniversary.

"Oh, I don't know if anything's going to compare to the first," Castle teases her about their steamy reunion.

The fall finale will revisit Beckett's secret LockSat investigation that has a possible connection to her current case. Kristoffer Polaha also makes his debut in the recurring role as a public defender.

And while Beckett conducts her investigation elsewhere on the ship, Castle does his own snooping around, going undercover as a passenger who signed up to perform in the cruise's musical show. Check out his great set of jazz hands in the video below.

"Castle" airs on Mondays at 10 p.m. on ABC.