Peeping Tom - 1960

Loner Mark Lewis shooting photographs of women , works in a picture studio also, through the night. He's making a documentary on panic, involving recording victims' responses as they are murdered by him. He befriends the girl of their family living underneath his, Helen, and he informs her vaguely about the movie he's making. She sneaks in to the flat of Mark and is horrified by what she sees especially if she is caught by Mark.