This signals the launch of Italian Neorealism, a method and style of political film making which would have an impact across the world. It's an unauthorised adaptation of James Cain's novel, The Postman Always Rings Twice which was sold to Hollywood in the early '30's but considered too hot to make under the Production Code.
A deadbeat drifter (Massimo Girotti) turns up at a shabby, desolate roadhouse run by an flabby middle aged chump (Juan de Landa) with a young, sexy wife (Clara Calamai) and a life insurance policy. And adultery turns to murder. It's not a thriller, and to an extent this is a love story between the two flawed, unscrupulous sociopaths.
Director Luchino Visconti was a Marxist (and an aristocrat) and most of all this is about spiritual corrosiveness of ignorance and poverty. It was made under unfavourable conditions with WWII going badly. The poor film stock and low budget renders a stark, distressed look, like a newsreel. Everything is sordid and authentic.
There are occasional longueurs. But this is a dirty, baleful cinematic landmark. The weak, impulsive protagonists are horrifying and Girotti and Calamai are intensely erotic and sleazy, reduced to their primal emotions; sex and greed. It makes the authorised MGM version (1946) feel like the work of the Children's Film Foundation.