La demoiselle et son revenant (1952)

Rosette is young and charming but she is crippled so she cannot make the most of her life. Which upsets Jules Petitpas, a single inventor, her eccentric but kind-hearted neighbor. Jules pledges to help her by creating a potion that will cure her. Unfortunately he dies before being able to achieve his aim. But a promise is a promise, and the good man comes back to the land of the living as an ... ectoplasm! And he manages to involve a whole tribe of ghosts to assist him in the noble task of saving the young lady. All is well that ends well.

Unfortunately the movie La demoiselle et son revenant is not yet available on HBO Max.