This is art-house horror, a pure cinema for connoisseurs, a return to late-19th-century decadence.

For all its gloss and panache and giddying crash zooms to the keyhole, Amer is finally little more than a prolonged tease of a movie; provocation without a purpose.

With its excitable score (assembled from old gialli), expressionist colour palette and invasive close-ups, it is heady, head-scratching fun.

This is probably why Cattet and Forzani only make a movie every four years. The wait is certainly worth the payoff.