Professor Bernard Quatermass, Director General of the British Experimental Rocket Group, launches the first manned space flight from Australia. A malfunction sends the rocket and its three man crew thousands of miles off course. When the rocket returns to Earth, it crashes in Wimbledon. To the shock of Quatermass, his team, and the spectators who gather around the crash site, only one of the three crewmen, Victor Carroon, is still aboard. Carroon seems unwell, barely able to talk. Examinations of the rocket by both Quatermass and Scotland Yards Inspector Lomax reveal that something attacked the crew of the rocket as they were on course back to Earth. Even more alarming is that Carroon seems to be undergoing some sort of metamorphosis, which is accelerated by a botched kidnapping attempt by foreign agents.