Oscar-winner Dean Jagger stars as a Quatermass-adjacent irascible scientist in this grittily thrilling science-horror from legendary Hammer writer Jimmy Sangster. Featuring spirited support from Leo McKern, William Lucas and Anthony Newley, X the Unknown has been painstakingly restored by Hammer in 4K from the original film negatives.

When an unlucky squaddie dies in agony from radiation poisoning, the Atomic Energy Commission despatch Dr Royston to investigate. Royston finds no trace of the deadly radiation, but it soon begins to claim new victims.