A research team from Ryan Electric Products moves into an old Victorian mansion to develop a new recording medium. As they explore the renovated Victorian room, they witness strange occurrences and Jill Greeley experiences a ghostly apparition trapped in a stone wall dubbed a "stone tape." Believing the tape holds the key to their discovery, team director Peter Brock decides to analyse and exorcise it, unleashing a darker force that threatens his team. The hypothesis of residual haunting - a recording of past events made by the natural environment - known as the "Stone Tape Theory" was inspired by this 1972 play.