Castle - Season 2, Episode 23: Soundtracks

Opening scene: the maid discovers a dead body.

0:09 Beckett and Castle go to Wilder's office to ask the staff questions.

0:40 Case solved; Castle looks for Beckett and sees her and Demming kissing.

WRONG EPISODE, very likely; I watched the whole episode, and then skipped thru it in 10-seconds steps, but never heard this song. -- Maybe you meant season 1, in episode 1, at Castle's book party?

Wilder's body is found by a cleaning woman.