Army captain John Dillon defies a clampdown to take the remains of a crashed object to Quatermass's British Rocket Group. Quatermass returns with him to the crash site - a huge domed chemical plant. While they are there, another small object crashes, a gas seeps out and a small bubble appears on Dillon's cheek.

Broadhead becomes the latest victim of the gas. Quatermass tricks his way inside the plant with Ward and Fowler. Ward gets separated and strays into one of the food domes - then emerges covered in a burning synthetic food, and dies. Back at the rocked base, Pugh has discovered the origin of the objects - an asteroid on the dark side of the Earth.