 When a skull is found during building works at Knightsbridge, London, the work is halted in order that a full archaeological dig can proceed. The diggers delve deeper, finding more skulls, but also finding some form of tube-like shell made of a ceramic like material. The Ministry of Defence believe it to be an un-exploded bomb, but when they manage to dig inside the shell, dead insect-like creatures are found. The MOD continue with their story, but Professor Quatermass s theory that the insects are Martians who visited Earth over five million years ago is proved to be correct with drastic consequences.