The Bird with the Crystal Plumage (1970)

Sam Dalmas is an American writer vacationing in Rome with his English model girlfriend Julia. Suffering from writer’s block, Sam is on the verge of returning to America, but witnesses the attack of a woman in an art gallery by a mysterious black-gloved assailant dressed in a raincoat.

Attempting to reach her, Sam is trapped between two mechanically-operated glass doors and can only watch as the villain makes his escape. The woman, Monica Ranieri, the wife of the gallery’s owner, Alberto Ranieri, survives the attack and the local police confiscates Sam’s passport to stop him from leaving the country; the assailant is believed to be a serial killer who is killing young women across the city, and Sam is an important witness. Sam is haunted by what he saw that night, feeling sure that some vital clue is evading him, and he decides to help Inspector Morosini in his investigation. He interviews the pimp of a murdered prostitute and visits a shop where one of the victims worked. There, he finds that the last thing she sold on the day of her death was a painting of a stark landscape featuring a man in a raincoat apparently murdering a young woman. He visits the artist, but finds only another dead end.