Space: 1999 - Season 2 (1989)

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.

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 unless they supply him with enough nuclear fuel to sustain him "forever".

The tall and imposing Magus arrives on board the ship. He claims godlike 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 illogical at that, who needs to be controlled.

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.

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 super-strength, one which can render itself invisible, and one which can teleport.

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.

The expansive Taybor, an intergalactic merchant arrives from hyperspace on his ship, The Emporium. He is offering to sell things to the Alphans. Koenig realizes that if the Taybor sold them his spaceship, it would enable the Alphans to fly back to Earth, but the price the Taybor is asking for this transaction is Maya.

Whilst he is exploring an asteroid Koenig is taken over by an alien race known as the Kalthon, who replace him with an exact double. In consequence every action ordered by the fake Koenig is solely for the benefit of the Kalthon and to the detriment of the welfare of the Alphans. Helena realizes that something is wrong when 'Koenig' is cold to the touch and needs to convince the other crew members.

Alpha is on the verge of being destroyed by intense shockwaves emanating from a planet they are approaching. The Alphans land on the planet, seemingly devoid of any human existence but being run by a group of machines. The machines explain to the visitors that their human overlords are in a state of regeneration but the chief machine, the Guardian, sees the Alphans as a threat and it is down to two newly regenerated females known as A and B to decide their fates.

Ship's engineer Patrick Osgood believes he can obtain tiranuim to make a new heart for his sick wife Michelle, from the catacombs of the moon, using explosives. The explosion which follows gives him a vision of the future in which the moon is destroyed by a fireball and a sudden heat storm strikes. Though Helena is making a new heart for Michelle, its repeated failures cause Osgood to become impatient. Convinced he is his wife's only salvation, he drags Michelle down into the catacombs, giving Koenig a double task - to avoid the fireball and save the Osgoods.

Koenig and Verdeschi are sucked into a space warp. A feverish Maya is stricken with a fever that causes her to transform into a repulsive space monster.

Several crew members explore the planet Sunin, including botanist Shermeen Williams, who appears to have visionary gifts. She links up with an alien, called Vindrus, who wants her help in transferring his body and that of his race into solid matter, giving them proper human form so that they can join the universe as real matter. However, for every one of his race made flesh, an Alphan must lose their matter.

A strange cloud drifts over the base and causes most of the crew to be stricken with illness. A monster, the 'cloud creature' appears out of the cloud and runs amok on the base. A voice from the cloud explains its purpose. The base must give up its life support in order to prevent the cloud from dying. With most of the crew indisposed through illness, it is down to Maya to employ her shape-shifting skills to beat the creature.

Lambda waves permeate Moonbase Alpha, causing instruments to malfunction and people to behave out of character. Crew member Sally dies in mysterious circumstances. Koenig is assailed by guilt-driven visions from his own past. It eventually becomes clear that the Lambda Variant has amplified psychic abilities on the base, in particular for Carolyn Powell, whose lover was previously Sally's boyfriend, and who is beset by jealous rage. Dr. Russell aids Koenig to overcome his own "ghosts", and prevent Carolyn from taking over the Moonbase.

While unconscious and connected to an experimental brain machine, Koenig dreams that he and his friends are on the way home. Upon awakening everyone appears to be hideous monsters.

Koenig convinces Helena and Maya that their supposed rescuers from earth are really hostile aliens who want a nuclear explosion on Moonbase Alpha.

Some subterranean miner start chanting for a planet that will cause the Moon to pass through a nebula deadly to those living at Moonbase Alpha.

When a ship carrying a prisoner lands at Moonbase Alpha after asking for assistance, Maya insists that the prisoner is a poet and not a murderer and releases him.

After investigating a planet where all humanoid life had been eradicated, Koenig becomes trapped in a prison on one of the moons where no one knows that their planet has been wiped out.

The arrival of the Alphans on another planet seems to cause a change in its atmosphere, setting off pollution and poisoning of the water. They meet Zoran, the sole survivor of the last exploratory force, who tells them that the planet is controlled by an immortal being - with whom Koenig must parley if he and his crew are to leave the planet alive.

The Dorcans demand that Moonbase Alpha hand over Maya so that the use of her brain stem can continue their immortal existence.