The Cupboard Was Bare (1948)

Original title: L'armoire volante

The aunt of Alfred Puc, a meek tax-collector in Paris, dies while riding in a moving van. The driver, not wishing to be bothered by a police interrogation, hides her corpse in a cupboard before notifying Alfred. But the van is stolen. Alfred, being the heir of a rich lady, begins a frantic search to locate the missing van and the cupboard because one can't claim an inheritance if there is no 'corpus delecti.' In his search, he gets caught up in an underworld web and finds the body of a murdered gangster in his room. He finally locates the cupboard but promptly loses it again. But, wait, it isn't "finis' time, yet.