Adventures of Kitty O'Day (1945)

Dragging along her spineless boyfriend Johnny, hare-brained secretary Kitty O'Day is unstoppable as she tries to determine her boss's murderer. In her exuberance she and Johnny keep running into more corpses, as well as the unbelievabley inept team of Inspector Clancy and his sergeant, Mike. Their luck seems to run out, though, as they deliver themselves right into the hands of the murderer.