The crew of Moonbase Alpha must struggle to survive when the force from a massive explosion throws the moon out of orbit and into deep space.
S01:E01 - Breakaway
Commander John Koenig, the new commander of Moonbase Alpha, leads the investigation of a mysterious disease at the station and uncovers evidence of a far greater looming disaster.
S01:E02 - Force of Life
A wandering energy force inhabits the body of Alpha technician Anton Zoref, turning him into an energy absorbing being.
S01:E03 - Collision Course
After destroying an asteroid on a collision course with the moon, an even larger obstacle appears - an entire planet! On a recon mission, John Koenig encounters an inhabitant who convinces him- on the basis of faith- that the moon and the planet must collide. But no one else supports Koenig's stand.
S01:E04 - War Games
Moonbase Alpha is attacked and devastated by warships from a nearby planet. With half of its population dead Alpha can no longer survive. Commander Koenig and Dr. Russel go to the alien world to plead for the survivors, but the inhabitants wish no one to disturb their serene existence.
S01:E05 - Death's Other Dominion
On the ice world of Ultima Thule the Alphans encounter members of lost earth expedition who have achieved immortality- but at a price!
S01:E06 - Voyager's Return
The Alphans encounter the Voyager space probe that has been wandering the cosmos propelled by the Queller drive- a faulty engine system. Following the probe is a fleet of alien ships from a world devastated by the drive.
S01:E07 - Alpha Child
The Alphans' joy turns to horror when the first child born on the Alpha matures into a five year old in a matter of hours. This is only a prelude to the arrival of formless alien fugitives- who plan to inhabit Alpha's population.
S01:E08 - Dragon's Domain
Discredited eagle pilot Tony Cellini is beset by recurring nightmares in which he was the only survivor of disastrous space mission. Now the moon is approaching the same set of circumstances that Cellini encountered.
S01:E09 - Mission of the Darians
The Alphans encounter a miles-long ark from the planet Daria, where the inhabitants have a very distinctive class separation.
S01:E10 - Black Sun
The Alphans take drastic measures to prevent the traveling moon from drifting into a black sun.
S01:E11 - Guardian of Piri
Contact is made with the planet Piri, where the main computer created an idyllic life that led to extinction of its population through apathy. Now John Koenig must fight to save Alpha as his people fall under the same fate.
S01:E12 - End of Eternity
While exploring a cavern in an asteroid, the Alphans release Balor, a sadistic alien who has achieved immortality.
S01:E13 - Matter of Life and Death
Dr. Russell's presumed-dead husband mysteriously reappears on a reconnaissance mission to a nearby planet.
S01:E14 - Earthbound
Simmonds forces Koenig to let him take the place of a dead alien on an Earthbound ship.
S01:E15 - The Full Circle
While exploring an Earth-type world several Alphans, including Commander Koenig and Dr. Russel, disappear after sighting a strange fog. Shortly afterwards a race of primitive humans are encountered.
S01:E16 - Another Time, Another Place
A sudden acceleration creates a duplicate moon complete with replicas of the crew.
S01:E17 - The Last Sunset
Communication from another planet dashes the crew's hopes of settling on a planet similar to Earth.
S01:E18 - The Infernal Machine
Helena and Koenig are imprisoned on a spacecraft to serve a machine for the rest of their lives.
S01:E19 - Ring Around the Moon
Maintenance technician Fred Clifford is possessed by an eerie yellow glow, which ultimately kills him. It transpires that it is coming from a planet called Triton, which captures the Alphans and insists that Helena should become the Eyes of Triton.
S01:E20 - Missing Link
Koenig's soul is captured and scrutinized by an alien living there.
S01:E21 - Space Brain
Koenig decides to use explosives to prevent a collision with an unseen intelligence.
S01:E22 - The Troubled Spirit
Dan Mateo, the Alphans' botanist, believes that he can communicate telepathically with his plants but collapses. He comes to and appears to be fit and well but he is turning into a murderous and disfigured ghost who has been taken over by an alien manifestation.
S01:E23 - The Testament of Arkadia
Koenig is faced with a tough choice when Moonbase Alpha's orbit ceases.
S01:E24 - The Last Enemy
Koenig arranges a cease-fire between warring planets when Moonbase Alpha is caught in their fire.