The guerrilla reappears on the grounds in a vortex-like effect, but is intercepted by two huge humanoid aliens, called Ogrons, who attack him and leave him for dead. UNIT soldiers discover the severely injured guerrilla and take him to hospital while the Doctor examines his weapon and a small black box that was found in a nearby tunnel system. Styles leaves for Peking, while the Doctor discovers that the pistol, an ultrasonic disintegrator, is made of Earth materials, not alien, and that the box is a crude time machine. As he tries to activate it, the vortex effect appears again and the guerrilla vanishes.. The Doctor and Jo spend the night at Auderly House to monitor any activity.