Drama set in an Italian prisoner of war camp during World War 2, where a group of British soldiers find their plans for escape thwarted by a mysterious traitor in their midst.

When Richard Logan, the partner in a safe making firm, is found unconscious, on an old deserted bomb site, he finds that he has no recollection of the last three weeks. Then he discovers that the private detective, hired by his wife, has been found murdered, and a safe that his firm installed in a large country house, has been cleverly opened, and the contents are missing. So with the help of his wife, he sets out to uncover the truth.

It is the end of the 18th century and smuggling is considered to be a legitimate spare-time occupation for most fishermen around the British shores. But when a gang of cut-throats, led by the infamous Black John (Bernard Lee) begins to lure ships onto the rocks of Smugglers Bay, and murdering their crews for the sake of loot, the fishermen begin to fear for their livelihoods. In desperation, they appeal to the local magistrate Squire Trevenyan (Peter Cushing).

In England, a group of space scientists led by Bernard Quatermass, who have developed plans for the first Moon colony, learn that a secret, ostensibly government-run, complex of identical design has been built in a remote part of England and is the focus of periodic falls of small, hollow "meteorites" originating in outer space. Quatermass determines to investigate and uncovers a terrifying extraterrestrial life form which has already begun action to take over the Earth.