He was haunted by a story in Life magazine about a pair of conjoined twins. In the photo the two girls sat side by side, one bright and open, the other dark and somehow wrong.

SISTERS (1972) was Brian De Palma's first real thriller after a career in counterculture comedy, made for half a million dollars on Staten Island.

Margot Kidder plays Danielle, a charming model, and Dominique, the twin she was surgically separated from. Across the courtyard, a reporter named Grace watches a murder happen in Danielle's apartment, calls the police, and returns with them to find the body gone and the crime denied.

This is where De Palma first used the split screen device that would become his signature, showing you the killing and its cover-up in a single divided frame.

He landed a real coup, too, persuading Bernard Herrmann, Hitchcock's legendary composer, to score the film, lending a $500,000 shocker the sound of a classic.