I told them all they were capable of believing.
Just as The Quatermass Xperiment begins with a young couple who narrowly miss being hit by a rocket from space, 1957's sequel, Quatermass 2, opens with a young couple, one of whom has been hit by something from space. Professor Quatermass, again played by Brain Donlevy, stumbles onto the scene (it's not his fault this time) and upon further investigation finds himself caught up in a conspiracy to infect the earth's inhabitants with alien creatures (hence the alternate American title Enemy from Space). John Longden replaces Jack Warner as the incredulous Inspector Lomax, Sydney James is the alcoholic reporter who quickly finds a reason to sober up, Bryan Forbes is the assistant who accompanies Quatermass on a fact-finding mission to a mysterious, remote plant and gets taken away by the guards, and William Franklyn is the rocket scientist working on Quatermass's moon project who ultimately saves the day.
This film, like the first in the series, was directed by Val Guest, but unlike The Quatermass Xperiment, Nigel Kneale had a direct hand in writing the screenplay for this outing (with Guest). By the time Hammer was ready to make Quatermass and the Pit a decade later, Kneale would be able to present his vision completely unfiltered -- and the special effects will have nearly caught up with him. Nearly.