Negatives (1968)

Used-furniture dealer Theo and his lover Vivien like to enhance their lovemaking by dressing up and role-playing. He pretends that he's notorious murderer Dr. Hawley Harvey Crippen; she pretends that she's either Crippen's wife Belle Elmore or his mistress, Ethel Le Neve. When they're not having sex, Theo and Vivien bicker vigorously and often, but continue to live together above Theo's London shop. One day Reingard, a female German photographer enters their lives. She's been observing the couple, whom she finds intriguing. She moves into one of the rooms above the shop; under her influence, Theo begins to shred his Crippen persona in favor of that of another notorious figure: German flying ace Baron von Richthofen, a development that threatens to impact Theo's relationship with Vivien.