2 seasons available
Koenig and Helena appeal to the daughter of an alien ruler planning to use the Alphans as fuel for a biological computer.
Bizarre capsules circling Moonbase Alpha contain ancient killers in suspended animation.
Helena, John and Alan travel back in time to plague-infested Scotland.
A race of superior robots forces Helena and Tony to teach it human emotions.
A willful computer forces Helena and Koenig to accompany it to a poisonous plane.
A godlike being offers the Alphans a chance to live on a planet resembling Eden.
Cryogenically preserved beings infect the crew with a deadly disease.
As punishment for destroying vegetation, Maya and Koenig are forced to battle three aliens on the planet Luton.
A living rock in desperate need of water enslaves Tony and paralyzes Helena.
A magical trader agrees to send the Alphans back to Earth in exchange for Maya.
Koenig is trapped in a crystalline asteroid cave, where his double emerges and returns to Moonbase Alpha.
The Alphans discover the cocoons of deadly chlorine-breathing monsters (Ina Skriver, Sarah Douglas).
A miner has vivid visions of his wife's demise and Moonbase Alpha's destruction.
Delirious Maya endangers herself and the crew by transforming herself into an array of fearsome creatures.
An ancient being (Stuart Wilson) tries to alter his race's fate by sacrificing the Alphans; guest Lynne Frederick.
Even Maya's (Catherine Schell) powers fail against a seemingly invincible creature that incapacitates the crew.
A cosmic cloud gives a crew member (Deborah Fallander) paranormal abilities; guest Jess Conrad.
Aliens disguised as friends from Earth trick all but Koenig.
Koenig and Maya fight to save Moonbase Alpha from deadly aliens.
A deranged crewman's (Ken Hutchinson) actions threaten to destroy the Alphans; guest Carolyn Seymour.
A spaceship arrives on Moonbase Alpha carrying a prisoner, whom Maya is astonished to learn is Dorzak, a survivor from her planet, Psychon; but she isn't sure that a man of peace can really be guilty of the crimes of violence he is being exiled for.
Answering a distress signal, Commander Koenig is forced to do a crash-landing.
Koenig must convince a powerful alien bent on destroying all visitors to set the Alphans free.
Alien troops invade Moonbase Alpha, seeking Maya's brain to extend their abilities and obtain immortality; guest Ann Firbank.
An explosion disintegrates the moon's dark side and hurls it, along with 311 occupants, out of Earth's orbit and into space.
Colleagues die when Zoref (Ian McShane), possessed with a consuming need for heat, extracts it from their bodies.
An ancient alien queen (Margaret Leighton) persuades Koenig to allow their moon to collide with her planet.
Koenig appeals aliens to allow the crew to settle on their planet after the aliens' attack leaves Moonbase Alpha inhabitable.
Commander Koenig and his colleagues speed through space and time into a world of ice; once there, they encounter people who appear to be former inhabitants of earth stranded there.
Revenge-seeking aliens complicate matters as the crew tries to incapacitate a deadly ship containing valuable information.
Cynthia's son (Julian Glover) turns out to be an alien seeking human bodies for fleeing fugitive space travelers to inhabit.
Cellini (Gianni Garko) tries to vindicate himself by proving the existence of a terrifying, tentacled monster.
The crew answers a ship's distress signal and discovers its occupants employing a gruesome survival technique.
Bergman (Barry Morse) brainstorms to stop Moonbase Alpha from being sucked into a deadly black sun; guest Paul Jones.
A beautiful woman (Catherine Schell) convinces all but Koenig to join her on a seemingly paradisiacal planet.
An immortal alien (Peter Bowles) released from exile by Koenig (Martin Landau) destroys all life it encounters.
Dr. Russell's presumed-dead husband mysteriously reappears on a reconnaissance mission to a nearby planet.
Simmonds (Roy Dotrice) forces Koenig (Martin Landau) to let him take the place of a dead alien on an Earthbound ship.
Several of the crew become Cro-Magnons after being caught in a time warp on a newly discovered planet.
Past and future overlap as a sudden acceleration creates a duplicate moon complete with replicas of the crew.
A verbal communication from the planet Ariel destroys the crew's hopes of settling on a planet apparently similar to Earth.
A machine named Gwent imprisons Helena and Koenig on a spacecraft to serve it for the rest of their lives.
Koenig must prevent an alien force on an obsolete mission from destroying Moonbase Alpha and its occupants.
After crash-landing on the planet Zenno, Koenig's soul is captured and scrutinized by an alien living there.
Koenig decides to use explosives to prevent a collision with an unseen intelligence.
A botanist's experiments in communication between plants and man bring bizarre and frightening results.
Koenig must decide if the crew should evacuate to an abandoned planet or escape when Moonbase Alpha's orbit ceases.
Koenig arranges a cease-fire between two warring planets when Moonbase Alpha and its crew are caught in their fire.