Episode Two: The Mark

Professor Bernard Quatermass and Captain John Dillon are investigating a mysterious government controlled, high security industrial plant in the English countryside when they witness an object, apparently a meteorite, falling to Earth a short distance away. They manage to find the spot where the object landed, and find it still intact. When Captain Dillon touches it, the object breaks, releasing a cloud of ammonia gas. Dillon inhales the gas and chokes. For an instant, Quatermass sees something appear on his face. When he looks more closely, he notices a small mark near the hairline.

While Dillon recovers, a platoon of armed guards appears. They take Dillon with them, and order Quatermass away. Reluctantly, Quatermass leaves and wanders the rubble where a village, Winnerton Flats, was raised to clear the land for the plant. He comes upon a tramp, who tells him about the building of the plant, and points out the remains of the 'meteorites' littering the ground. The professor collects some of the parts.

Quatermass makes his way to a nearby centre representing plant workers, where he tries to enlist help in rescuing Dillon. But the official at the centre is unsympathetic. A mother comes in to pick up her young daughter. The girl seems distracted and Quatermass notices she has the same mark he saw on Dillon. When the official becomes hostile, he leaves.

He returns to the laboratory, where his colleague Professor Leo Pugh has been experimenting on the remains of another 'meteorite'. Quatermass tells his daughter, Paula, who is dating Dillon, about Dillon's illness, but conceals the extent of his concerns. When Paula leaves the room, Quatermass fills in Leo about the plant and its military security. Leo shows him a reconstruction of the 'meteorite', which resembles a small spacecraft.

Quatermass heads for London to try to get police help, but is told the plant is outside police jurisdiction. Fowler, his contact at the Ministry, tells him that the plant is supposedly developing a synthetic food product. Fowler, who admits he too is uncomfortable about the plant, introduces him to Broadhead, a trade union official who has been conducting an inquiry into the plant. He reveals that similar plants have been seen in Siberia and Brazil.

Quatermass persuades Broadhead to get him on to the inquiry, where he discovers that the other members of the committee have the same mark on their faces...