First shown 11 September 1975. Written by Johnny Byrne. Directed by David Tomblin.
Director David Tomblin gives enormous urgency to this somewhat trippy episode in which technician Anton Zoref is taken over by an unknown alien force that seems to feed on energy. The production is top class turning what might have been something of a run of the mill story into much more. Tomblin utilises a battery of camera techniques to convey the strangeness of the alien while guest actor Ian McShane successfully menaces several Moonbase Alpha personnel sometimes with fatal results. At times its surprisingly graphic for what was seen as mostly a kids series with sudden freezing effects deployed to the alien’s victims. At the climax when Koenig orders all power to be switched off to try and isolate Zoref we see medical staff attempting to manually resuscitate a patient. Even more extreme, after a beam that was meant to finally fell the visitor resurrects him as charred with glowing eyes the results are a match for any horror movie of the day. That all this takes place in the comparatively bright environs of the base makes its use of scare techniques even more impressive.