After Private West (John Walker) screams, he tells Quatermass (Andre Morell) about the apparition he saw, and then passes out. He is taken away and revived. When he comes to, he tells Quatermass that what he saw looked like a dwarf. Barbara Judd (Christine Finn) begins reading some of the accounts she found concerning the nearby, supposedly, haunted house. Some of the descriptions talk about a figure that looked like a monkey or a dwarf that went across the room and through a wall. The newspaper report was from 1927. Some of the reports of hauntings go back as far as the eighteenth century.
Colonel Breen (Anthony Bushell) has his men dig further. In the mud, they find the door that belongs to the opening in the object. Tests on it show that it appears to be some ceramic type material that is harder than diamonds and can withstand heat over 3000 degrees, perfect for space flight. Still believing that the object is of Nazi origin, Breen is determined to get inside the walled off chamber. He brings in an expert with specialized equipment.
In the meantime, reporter James Fullalove (Brian Worth) learns that Quatermass is investigating the strange object found at Hobbs Lane. Inserting himself into the investigation he assists Quatermass and Dr. Roney (Cec Linder) in the search for information.
Whenever Breen and his men start mucking around with the wall to the hidden compartment strange sounds start echoing around the pit. Many of the men, including Breen and Quatermass experience vertigo and other physical ailments in response. Breen hires a civilian drill expert, Sladden (Richard Shaw) to work on opening the hidden door to the other compartment. Eventually Sladden manages to open the sealed compartment. Inside are three petrified insect-like aliens.
At the end of the episode, one of the aliens seems to lurch toward the open compartment door as if it is attacking the human men. This effect was an accident. The alien prop slid from its position unexpectedly which made it appear to be alive. The prop malfunction created one of the bigger scares in the series to those viewing at home. The actors were also taken aback by the sudden movement.