“Ring Around the Moon” is episode nineteen of season one of Space: 1999.
In Main Mission, a technician is fixing something when an orange ball appears on the horizon. It starts flashing, looking oddly like an eye. He drops his toolbox and heads to the computer and starts typing really fast. Sandra tells Paul who tells David to stop the man, Ted. David fails, as does Paul and Sandra calls the commander. Koenig fares no better, being pinned by one of Ted’s arms as the other continues typing. Dr Russell tries to intervene and tells Sandra to call security.
Ted stops, says ‘Help me’ and collapses, probably dead. The entire base shakes as the sphere emits a glow that encompasses the Moon. Sandra says that the sphere is not moving but getting closer. Commander Koenig says they are in orbit. A transmission is received, telling them not to resist. They are captives of the Black Triton.
The beam recedes and the commander takes reports; Alpha is not in great shape. The commander wants Paul to try and contact the sphere, the doctor to autopsy Ted and for Victor to come see him. He talks to Victor about paying the sphere a visit. Victor thinks they are being watched. Victor is right.
Koenig then pays a visit to medical where doctors Mathias and Russell says they found a pulsing light in Ted’s brain. But not much brain tissue; most was melted. There were changes to the brain that somehow allowed Ted to see and act as if he was a computer.
The commander wants Alan to take an Eagle for reconnaissance. Alan would prefer something more proactive than looking. A beam emerges from the sphere and envelopes his Eagle. When it recedes, the Eagle is tumbling back towards the Moon. Paul says they’re on manual; he can’t bring them in. It crash-lands not far from Alpha and Koenig leads a rescue party on foot. Mathias reports that the co-pilot, Donaldson, is dead.
Sandra tells Paul the scanners have all gone dead. He contacts the commander and tells him to come back; there may be an attack incoming. Koenig says they are more than halfway there and will continue. The ball appears again and Dr Russell is caught out in the open. The commander tries to help but is blown back.
The doctor is somewhere and a voice is telling her not to be afraid. Koenig comes around in medical and Victor tells him that Dr Russell is gone. The commander wants to get through the forcefield somehow. He says the Black Triton could just come and take what it wants.
The doctor is talking to whoever took her. They say they are the eyes of the planet Triton. Everything that is or will be is recorded by them. That is what they need Dr Russell for.
The commander talks to Alan. Alan thinks Paul brought them in. Koenig tells him their Eagle was on manual; Alan must have brought them in. Alan says he was in no fit state.
Koenig wants to get through the forcefield. The first attempt does not work. Then Dr Russell is returned anyway. Dr Mathias reports she’s okay – but she’s also blind. With the side-effect of still being able to see. She’s been affected like Ted was, though not as immediately fatally.