Seasons & episodes
S1 · E10Black Sun 1975-11-06 · 52 min
The travelling Moon drifts within range of a black sun. Pulled toward certain destruction by its inescapable gravitational force, the Alphans employ desperate measures to stay alive. As a lifeboat Eagle carries six persons to safety, the Moon plunges into the black sun, with only an experimental forcefield protecting Alpha.
S1 · E11Guardian of Piri 1975-11-13 · 52 min
Strange events befuddle the Alphans as they approach the planet Piri. When exploring its lifeless surface, Koenig encounters the seductive servant of the mysterious Guardian of Piri. She offers the wayward Alphans a life of peace and perfection. Realising the deadly truth behind the peace of Piri, Koenig struggles to free his people from the Guardian's influence.
S1 · E12End of Eternity 1975-11-20 · 52 min
While exploring an asteroid, the Alphans injure an alien trapped within. Bringing him to Alpha, they discover his wounds have completely healed. The indestructible Balor is a scientist whose people had discovered the secret of immortality. Balor is a psychopath, offering a drastic solution to his people's apathy; now freed of the eternal prison, he plans to spend eternity practicing the art of pain and torture, with the Alphans as his subjects.
S1 · E13Matter of Life and Death 1975-11-27 · 52 min
A lush Earth-type planet holds the promise of a new home for the people of Moonbase Alpha. When the reconnaissance Eagle returns, it carries an unexpected passenger: Helena's husband, who died five years ago. The mysterious Lee Russell tells the Alphans that death awaits them on the new planet. The Alphans ignore his warning and unknowingly descend into a world of antimatter.
S1 · E14Earthbound 1975-12-04 · 52 min
An alien spacecraft crashlands on the Moon, its passengers refugees from a dying world. As their destination is Earth, they generously offer to take one person with them when they depart. The scheming Commissioner Simmonds takes steps to ensure that he is the lucky individual chosen, even if it means destroying Alpha.
S1 · E15The Full Circle 1975-12-11 · 52 min
When exploring a habitable planet, members of the Alphan survey party vanish without a trace. Are they the victims of an indigenous tribe of Stone Age humanoids? The mystery deepens when a dead caveman is found to have capped teeth. Others soon notice the primitive cave chief and his mate bear an uncanny resemblance to the missing John Koenig and Helena Russell.
S1 · E16Another Time, Another Place 1975-12-18 · 52 min
After an encounter with a space-time anomaly, the Alphans find their Moon back in the Solar System on a course to re-enter Earth orbit. The celebration ends when it becomes apparent Earth is an inhospitable wasteland. The mystery deepens when they discover a duplicate Moon already in orbit and a duplicate Moonbase Alpha lying empty and deserted.
S1 · E17The Last Sunset 1976-01-01 · 52 min
Anonymous alien benfactors provide the wandering Moon with a breathable atmosphere. The Alphans rejoice as they realise they have a wonderful new home in their own backyard. Preparations are made to settle and begin building a new civilisation on the Moon's surface. Koenig is suspicious of the aliens' motives, wondering how long this generous gift will last.
S1 · E18The Infernal Machine 1976-01-08 · 52 min
The Alphans are visited by a bizarre spacecraft, whose request for supplies hides a deeper purpose. The ship, Gwent, is found to be sentient, the attempt of a vain alien genius to live forever. Powerful, unstable and craving companionship, Gwent intends for Koenig, Helena and Bergman to replace its aged, dying creator.
S1 · E19Ring Around the Moon 1976-01-15 · 52 min
A technician falls under an alien influence, accessing classified information before mysteriously dying. Soon after, the Moon is stopped in space by the powerful rays of an alien spacecraft. The aliens' only interest in Alpha is the data held in its computers, information they now plan to obtain through the possessed eyes of their next agent: Helena Russell.
S1 · E20Missing Link 1976-01-22 · 52 min
John Koenig finds himself trapped on the planet Zenno, in the home of an alien scientist and his daughter. Advanced two million years beyond Earthmen, the aliens consider Koenig their missing link. Faced with the threat of being treated like an experimental animal for the rest of his life, Koenig uses an unexpected weapon to confound his captor: love.
S1 · E21Space Brain 1976-01-29 · 52 min
An Eagle and its crew are crushed to death by an enormous energy field in space. When one of Alpha's astronauts is possessed by the anomaly, he tells them the energy field is a living space brain, which responded to the 'threat' with antibodies Finding the Moon on a collision course with the Brain, the Alphans make plans to avoid the same fate as the Eagle.
S1 · E22The Troubled Spirit 1976-02-05 · 52 min
Dan Mateo, hoping to unlock the secret of communication with plants, unleashes a killing force from the depths of his own mind. This macabre spectre seeks vengeance for Mateo's horrible death—which has not yet occurred. Bridging the span between science and the supernatural, the Alphans hope to break the cycle and exorcise the ghost without killing the man.
S1 · E23The Testament of Arkadia 1976-02-12 · 52 min
The wandering Moon suddenly changes course and comes to a halt in the vicinity of a dead world. As Alpha's power fails, the only hope for survival is to evacuate to the planet, which was ravaged by a nuclear war in the distant past. Searching for answers, a team is sent to the surface, where they discover the shocking truth of the origin of Mankind.
S1 · E24The Last Enemy 1976-02-19 · 52 min
The Moon approaches a solar system with two planets on opposites sides of its sun. The Alphans are trapped in an interplanetary conflict when warships from both worlds trespass on the Moon to fire missiles at their opponents' planets. After taking in a refugee from a destroyed gunship, the Alphans discover they have drifted into the middle of a literal war of the sexes.
S2 · E1The Metamorph 1976-09-04 · 51 min
An Eagle is sent onto the surface of the planet Psychon, which has titanium, needed for repairs to the Alpha Base. It fails to return and is used by Psychon scientist Mentor as a bait with which to entice other members of the Alphan crew onto the planet. Mentor is building a computer but it will be fuelled by the living brains of humans, and he has his eye on those of the Alphan crew. Fortunately his daughter, the shape-shifting Maya, does not share her father's views and is on the side of the Alphans.
S2 · E2The Exiles 1976-09-11 · 51 min
With Maya now a crew member the Alphans discover a young couple called Cantor and Zova who have been in suspended animation for some while. They claim that they are exiles from the planet Golos, following an invasion, and ask for the help of Alphan crew members to restore the planet to them. Helena and Tony accompany them to the planet Golos, where it is apparent that they are not the young innocents they appeared to be.
S2 · E3Journey to Where 1976-09-18 · 51 min
A transmission from Dr. Logan in Texas City leads the Alphans to believe that they can finally land back on Earth, though they have travelled through time and, when they touch down in Texas City, they will be in the twenty-second century. However, due to a hitch, they find themselves in a barren and hostile environment. It is Scotland in the fourteenth century where the Scots are at war with the English invaders.
S2 · E4One Moment of Humanity 1976-09-25 · 51 min
A sinister woman called Zamara materializes on the base, forcing Helena and Tony to accompany her to the planet of Vega, whose natives are anything but friendly. A servant of the Vegans, known only as Number Eight, informs the two Alphans that he and his race are the natural inhabitants of the planet and that Zamara and her race are androids, who, it turns out, want the Alphans to teach them warfare.
S2 · E5Brian the Brain 1976-10-02 · 51 min
The Alphans encounter an eccentric and intelligent robot who is known as Brian the Brain. Brian's creator Captain Michael and his crew have all died in mysterious circumstances and Brian asks for the help of Koenig and his crew. However, it soon becomes very apparent that Brian is anything but harmless and was in fact responsible for the deaths of Captain Michael and his colleagues. And he is ready to do the same to the Alphans.
S2 · E6New Adam New Eve 1976-10-09 · 51 min
The tall and imposing Magus arrives on the base. He claims god-like powers, namely that he effected the Creation. But he is now disillusioned with the way that Life has progressed and wishes to start again. He plans to mate Helena and Tony and Maya with Koenig. But of course he is not God but a renegade cosmic sorcerer, and quite an illogical one at that, who needs to be controlled.
S2 · E7The Mark of Archanon 1976-10-16 · 51 min
The latest extra-terrestials to be rescued by the Moon Alpha Base crew are Pasc and his young son Etrec. They are from the usually peaceful planet of Archaron and they claim that they are victims of a rebellion, engineered by Pasc's wife Lyra. However, Helena discovers that they have both been infected with a virus which makes them considerably less friendly and more deadly than their initial claim.
S2 · E8The Rules of Luton 1976-10-23 · 51 min
Whilst Koenig and Maya are exploring a planet called Luton,which is lush in vegetation, she picks a flower and he helps himself to some fruit. As a result they are put on trial for murder by three talking trees, the Judges of Luton. The trial is by combat and the pair must face three aliens, one with superstrength, one which can render itself invisible and one which can teleport.
S2 · E9All That Glisters 1976-10-28 · 51 min
The Alpha Moonbase needs a rare ore known as Milgonite, which is detected on an extremely dry planet. Koenig leads a small landing force and discovers a glowing rock formation which comes alive and cuts off the party's links with the base. It is a trap - the planet needs water to survive and has lured the travellers there for the water in their bodies.