"The Great Moue Detective" movie.
Vincent Price does the voice of Ratigan, the evil doer in the story.
He recorded this song, to a vinyl record, in preparation of being able to trap Basil, the detective,
and execute his plan to execute Basil.
It the record plays while Basil and associate, it trapped.
Ratigan explains to Basil how the execution will happen.
Music by Henri Mancini
I didn't understand the song until I read the reason for the song.

You know what happens when someone upsets me?’
Vincent Price gives what must be his finest vocal performance as the cape-swirling villain, Professor Rattigan (whose ultimate design was informed by Price’s performance in 1950’s Champagne for Caesar), and gets to sing two original songs written by the legendary Henry Mancini: The World’s Greatest Criminal Mind and Goodbye So Soon. Listen to them below.

A more cheerful and upbeat version of the song is heard sung by a chorus during the film's closing credits.