The story is set in the 1930s, reflecting on the original Max Fleischer style of animation.
Betty works as a waitress in a diner with her friends Bimbo the musical dog and Koko the Clown.
While searching for a new job they bump into detective Sam Slade, who hires Betty and her pals to go undercover for him as musical detectives to keep an eye on Hollywood movie star Lola DaVille's diamond necklace.
Bimbo and Koko break Betty out of jail, then head over to Moolah Studios where they find out that Lola's secretary, Miss Green, was behind the robbery, and that her accomplice was the detective Sam Slade.
The pursuit ends on a Busby Berkeley set, Lola DaVille receives her diamond necklace and Sam Slade and Miss Green are both arrested by the police.