Professor Quatermass, trying to gather support for Moon colonisation his project to colonize the Moon, is intrigued by the mysterious traces that have been showing up on his radar - meteorites crashing down?. Following them to the place where they should be landing he finds a destroyed village, a mysterious factory too close to his designs for the Moon colony for comfort, and some strange, aerodynamic objects containing a mysterious, ammonia-based gas that infects one of his assistants. Officially, the factory is producing synthetic food; but despite the veil of secrecy surrounding it Quatermass succeeds in finding out it harbours aliens with deadly designs on the Earth... Second in Hammer Films' trio of screen versions for Nigel Kneale's classic 1950s BBC serials, with the same director and star as 1955's "The Quatermass Experiment".