This is the script of the third television serial involving Professor Bernard Quatermass. The Quatermass Experiment and Quatermass II have already been published. The same central character appears in all these, but otherwise they are not connected.

When this story opens Quatermass is in London for conferences at the War Office. His rocket research station, hitherto purely scientific in its objects, is being taken over by the military for the furtherance of a terrible space-war project to be known as the Dead Man's Deterrent.

But the nation whose destiny they are discussing has its attention on the past. The news topic of the moment is a building site at Knightsbridge, where excavations have uncovered fossil bones of man-apes estimated to be five million years old. Then, at a still deeper level in the pit, something else is found which is soon claiming Quatermass's expert attention. It leads him through encounters with superstition, ritual, and magic - to a new and alarming conception of the very nature of humanity.