Dr. George Dumurrier (Jean Sorel) runs a clinic, and is looking after his ill and neurotic wife, Susan (Marisa Mell). After her death, George and his mistress, Jane (Elsa Martinelli), arrive at a nightclub to see a performer named Monica (also Marisa Mell), who could be the twin of the late Susan. George and Jane. through various subterfuges, try to find out if Monica and the supposedly deceased Susan are indeed one and the same. But the police are certain that Susan is really dead -- and that George murdered her. One On Top of the Other is a twisty, far-fetched suspense tale that has an interesting idea (the type of thing that British screenwriter Jimmy Sangster might have come up with) but mediocre execution. The movie features interesting performers but it needs a different musical score and much more tightness in both the direction and editing. Still, there is some tension at the very end. Handsome Sorel [A View from the Bridge] is a good actor who deserved much better assignments than this. Alberto de Mendoza also gives a good performance as George's brother, Henry. John Ireland [Raw Deal] shows up now and then as a San Francisco police inspector, and a (deliberately) haggard-looking Faith Domergue is cast -- and appears even more briefly -- as George's grieving sister-in-law. Domergue and Ireland both appeared in The House of Seven Corpses five years later, in which Domerque was allowed to look much more attractive than in this.
Verdict: The plot and Sorel keep this going. **1/2.