Quatermass and the Pit

Professor Quatermass is resisting the planners of a rocket project known as the Dead Man's Deterrent. Meanwhile excavation is going on at Hobbs Lane, long the site of reported imps and devils.

Uncovered, they discover that the interior of the object is empty, and a symbol consisting of five intersecting circles, which Roney identifies as the occult pentagram, is found etched on an interior wall which appears to hide an inner chamber.