A planetomic missile has been fired at Earth from Planet 46, capable of destroying the whole world. The crew of Fireball XL5, on their way back to Earth, destroy the missile and head for Planet 46, where Steve Zodiac and Venus are captured by the Green Men, the Subterraneans who seek to destroy Earth. They launch another missile, this time with Venus aboard, but Steve manages to escape and takes the leader of the Subterraneans with him. He is able to rescue Venus and destroy the missile before it reaches Earth.

Several space tankers have been put out of action, their pilots in a hypnotic trance. The crew of Fireball XL5 escort another tanker and themselves become victims of a hypnotic light and voice. Robert the Robot is immune and takes control of the spacecraft. The crew again fly the same route, this time blocking out the hypnotic light and discover that the hypnotic power is coming from a huge brain cell, like an octopus. It needs heat to live and Steve manages to overcome the hypnotic power and destroys its heating plant.

Steve Zodiac and Venus, together with Robert the Robot, land in Fireball Junior on the Platinum Planet, to take the King of the planet up to the orbiting Fireball XL5 and to Earth for trade talks. Volvo, aide to the King, wishes to go to war with Earth and plants a bomb inside Robert. He refuses to reveal to Steve where the bomb is, so Steve takes him with him on the journey back to Earth. Volvo is forced to reveal where he planted the bomb and Steve is able to remove it and eject it into space.

Fireball XL5 is sent to investigate the disappearance of Fireball XL7. The Moon is pulled out of orbit and XL5 is taken with it to Planet Magneton, with the most powerful gravitational pull in the universe. They discover a huge power house, being fed by a giant electro-magnet on a crane, with pieces of Fireball XL7. The invisible people of the planet, the Solars, plan to puL the Moon into their orbit and bring light to their dark world. Steve overcomes them with his ray gun and reverses the power, sending the Moon back to its Earth orbit.

A flying saucer leads the crew of XL5 to Membrono, a planet doomed to be destroyed by another planet which has come out of its orbit. An old man sent the saucer to lure Steve Zodiac to the planet where, through Robert, he asks him to use the powerful missiles of Fireball to destroy the drifting planet before it destroys Membrono and in turn his own world which is governed by it. Hearing this, Steve is able to help the old man and save his peaceful planet.

A missile from space lands at Space City, but it doesn't explode. Soon, a quick-growing plant is covering Space City. Hormone from the planet Hedera will destroy it, but when the crew of XL5, with Doctor Rootes who has just arrived at Space City after experimenting with plants in space, land on the planet they are met by a plant man, the creation of Doctor Rootes who has become obsessed by plant life.

Sun worshippers, the Rejuscans, fear that missiles from Space City, being used to destroy dangerous meteorites, will anger their God. They destroy the launching site at Space City and when the crew of Fireball XL5 land on their planet in Fireball Junior to investigate, they capture Venus and attempt to kill her by strap ping her to the altar in their sun temple, in the path of the sun's rays. Steve Zodiac and Zoonie are just able to rescue her!

Venus and the Space City Engineer Jock are taking a team to New Earth, aboard the Mayflower III, where they hope to set up equipment to make the planet suitable for human life. The evil tiny inhabitants of the planet, the Lillispations, plan to prevent this and are able to trick Venus by imitating the voice of Steve Zodiac. They make Robert destroy the ship's oxygen pills – needed to save Jock's life – but Steve becomes suspicious and goes to the planet in XL5. Zoonie soon has them captured and Steve is able to save Venus and the other patrol members.

Fireball XL2 has disappeared and the crew of XL5 are sent to find it. They receive a distress call from the planet Monotane, where Steve and Venus, landing in Fireball Junior, find the wreckage of XL2. A storm forces them into a cave where they find the crew of XL2 who tell them that a monster caused the crash and is now outside the cave. Professor Matthew 'Matt' Matic lands in Fireball XL5 and is forced into the cave. Steve tries to escape but it is up to Zoonie to save the day.

A circus visits Space City and the special guests are Madame Mivea and Cosmo the Clown – really Mr. and Mrs. Space Spy in disguise. They plan to use the circus to allow the Nomadians to take over Earth to provide a home for them. Steve Zodiac's trapeze wires are tampered with and when they snap Jock just manages to save him by shooting out of a cannon and grabbing his dangling ankles! The Nomadian leader captures Lieutenant Ninety but just when things seem lost, one of Professor Matic's experiments explode and Venus wakes up. It was all a dream.

Fireball XL5 is sent to help the two survivors of a planet who are being attacked by a fish man, armed with a poisonous smoke gun. The crew arrive to find the glass city of the planet destroyed and no sign of the two survivors. The fish man attacks but is driven off. They find the survivors in an underground shelter but the fish man attacks again. Steve and Venus are just able to drag the survivors away from the poisonous fumes of the smoke gun and Steve is then able to use his stun gun to overcome the creature.

Fireball XL5 is ordered to take over the patrol duty of XL9 which has been attacked and damaged. The crew make their way to the nearest space station to refuel but find it empty. Mr. & Mrs. Space Spy have taken over the station and plan to use Venus as a hostage to steal XL5. Their ship, the S.S. Thor, was responsible for the attack on XL9. All seems lost until a rocket is placed in the sole of Mr. Space Spy's magnetic boots, sending him into orbit. Mrs. Spy takes the S.S. Thor to rescue him.

Space Pirates, based on the planet Aridan, are holding up freighters from the nearby planet Minera. Steve Zodiac plans to take a spacecraft and trick the pirates into thinking it is another helpless freighter. The Pirates overhear this and manage to knock Steve out. Robert is sent back to Space city as proof that they are holding Steve as hostage. Professor Matic and Venus deliver fresh water supplies to the Pirates but it is drugged.

The spy Grotham Deblis steals some top secret plans but is captured by the crew of XL5 and sentenced to 20 years imprisonment on the prison planet Conva. Mr. and Mrs. Space Spy trick Steve Zodiac and capture Professor Matic and force Steve to hand over Deblis who they plan to trick into revealing where he hid his plans. Deblis takes them to the volcanic planet Volanda where he has hidden the plans. He double-crosses Mr. & Mrs. Spy and Steve is able to rescue Professor Matic and recapture Deblis.

Two crooks manage to steal isotopes from Space City. The crew of XL5 go after them to the Planet Conva, but there is trouble on the planet. Steve tricks the crooks into thinking that they themselves are crooks and have stolen Fireball XL5 but the leaders of the gang are Mr and Mrs. Space Spy who recognise the crew of XL5 and order their death in a water chamber. The controller of the planet, General Shan, is able to rescue the crew and capture Mr. and Mrs. Space Spy.

Kudos, the last inhabitant of the planet Zanadu, is determined to kill all Lazoons. He used Major Jim Ireland, an explorer, to give Zoonie the deadly milomytosis virus. Steve realises that Ireland must be responsible and forces him to reveal the antidote — water from the fountain of life on Zanadu. The crew of XL5, with Ireland, go to the planet, stun Kudos and give the antidote to Zoonie. Kudos' spell of eternal life is broken and he becomes an old man.

Subterraneans One & Two plan to use a robot bird, fitted with deadly radium capsules, to kill Steve Zodiac in revenger for the capture of their leader. They send out radio signals from Planet 46 which the crew of XL5 then check out. Steve soon becomes ill and Venus finds a tiny capsule of radium in him. The robot bird tries again to kill him but Steve is able to use a stun gun to damage it. A high-pitched noise is heard, the same as the one that came from Planet 46. Steve threatens to use the bird on the Subterraneans but they agree to keep peaceful.

Nuclear explosions are coming from the planet Triad and the crew of Fireball XL5 are sent to investigate. They crash land in Fireball Junior and find that they have run out of fuel. They find themselves in a giant jungle and are forced into the trees by a giant tiger to be rescued by 2 giants, Graff and Snaff, who tell them that their experimental rocket fuel keeps exploding — the nuclear explosions. Their fuel is causing the problems and the XL5 team are able to change it and use it to refuel Fireball Junior.

A bomb planted aboard Fireball XL5 puts the spacecraft out of control. Ultra Arcon and Arcon Commander, from the planet Electron, move in with the Gamma spaceship and use their gamma ray to transport the crew of XL5 to their spaceship and off to the planet Electron. Steve finds a pair of Arcon glasses which protect the wearer from the gamma rays and they escape, stealing the Gamma spaceship. Steve is forced to use the gamma ray on Commander Zero who is about to attack their stolen spaceship.

The crew of XL5 land on a misty planet in response to a distress call. Steve Zodiac, on his jetmobile, finds a beautiful woman, Aphros, who tells him she has been exiled to the planet and wants to go to Earth. When Steve tells her this isn't possible she drugs him and threatens to activate the volcano that is nearby. Professor Matic fires an interceptor at the cave which explodes but Steve is able to escape and take Aphros prisoner. Holding her in the Space Jail they return home.

Lieutenant Ninety is trying to win his astronaut wings and his final test is a solo orbit of the Moon but something goes wrong and his capsule explodes. He is just able to eject but the crew of XL5 can't find him. Just when they are about to return to Earth, Professor Matic picks up the drifting Lieutenant on his spacemascope. Steve is able to rescue him and he is taken to the Sick Bay in XL5 where Commander Zero is happy to present him with his astronaut wings.

Steve Zodiac, Venus & Mathew Matic arrive on the beautiful planet Olympus for a holiday. At a birthday party given by Jankel, the chief of Olympus, for his son Ergon his enemy Kanerick, chief of the dark planet Kemble, poisons Ergon and takes Venus hostage back to Ermble. Venus is the only one who can save Ergo and Kankel forces Steve to rescue her by holding Matic hostage. This he does but they are only just able to battle through a violent storm to get back to Olympus and give Ergo the antidote.

The crew of Fireball XL5 diver the wreckage of the TA2, a spaceship which disappeared 50 years ago. A map found in the wreckage reveals that the pilot, Colonel Denton, intended to go to the planet Arctan after ejecting. On the planet the crew are captured by two ice men and put on trial for trying to steal their king who is Denton. He orders their release and Steve Zodiac offers to take him back to Earth but he does not accept.

The crew of XL5 are sent to investigate a new planet which suddenly appears and then disappears. Fireball XL5 is pulled across the planets and when the crew are able to leave when it slows down, they find that everything around them is in total blackness. A glass door in the blackness reveals a corridor which leads to a room. Suddenly, two domeheads, Magar & Proton, appear and tell the crew that they cannot be allowed to leave their planet and that their Earth memories will be erased. Robert is put on a conveyor belt leading to a furnace but is able to escape and rescue the crew.

An ultrascope which can look into deep space picks up the planet Nutopia which is said to be the perfect planet and two Nutopians use their travel transmitter to capture Professor Matic and his assistant Doctor Stamp and then Steve and Venus. On Nutopia, the two aliens, Privator & Perfectos, bothwant to keep Venus as their eternal companion. A duel follows which leads to them both being rendered helpless which enables Steve and his friends to return to the Space Observatory.

Doctor Baker and Doctor Simpson have just finished their experiments on the glass-surfaced Planet 73. Suddenly they discover that 6 Granatoid tanks, hostile robots, are coming towards the base and they send a message to Space City for help. On board Fireball XL5 the crew discover that Ma Doughty, owner of the Space City Music Shop, has stowed away. When they reach the planet when Ma Doughty appears the tanks begin to retreat! She is wearing pearls made from the rare mineral Plyton, the only thing which the Granatoid tanks fear.

After surveying the derelict planet Pharos, the crew of XL5 return to Space City to be told to take some Vesivium Nine, the greatest explosive in the universe, back to the planet & destroy it. When Steve and Professor Matic set the explosive in one of the many mines on the planet, they discover that the entrance has been blocked by the Subterrains. Robert is unable to clear the entrance so Steve uses one of the capsules of his ray gun as an explosive to clear their path. The crew are just able to leave the planet before it explodes.

Steve, Venus and Commander Zero enter Professor Matic's latest invention, a time machine. Suddenly, the door closes and Zoonie is playing with the controls. They find themselves back in 1875, in a western town. Steve becomes a Sheriff and Venus a woman bandit called Frenchie Lil, with Commander Zero as her accomplice. When Venus & Zero rob a bank, Venus is knocked unconscious. Professor Matic is able to bring Steve and the Commander back but not Venus as she is unconscious. He increases power and just before his machine explodes, Venus returns.

Someone is sabotaging robot freighters and Commander Zero and Steve Zodiac suspect it is the Biggs Brothers of the Space Salvage Company. Steve discovers Jock's new assistant, Edeundo, is planting the bombs in a freighter and duly handcuffs him there. He then forces the Biggs Brothers to the freighter and handcuffs them as well He tells them that a bomb has been put in the ship and will go off if they don't confess. With only 13 seconds left, Edmundo confesses but the 'bomb' isn't a bomb — just a musical box!

While Steve and Venus are on holiday Jonathan Zero is looking after Zoonie and when, with Zoonie, he goes into the main control cabin of Fireball XL5 one night, Zoonie gives the order 'Full Power'. Robert obeys and launches the spacecraft. This starts an alert and soon Commander Zero and Lieutenant Ninety are flying after XL5 in Fireball XL1 They find it in space, on fire, and when they get aboard they discover the fire out with Jonathan & Zoonie unconscious. Zoonie has put the fire out with a ray extinguisher.

The crew of XL5 are sent to the planet Floran to explode an Ellvium bomb in the atmosphere to kill Planitoid 3, a plant disease, so that plant life can be restored. When the bomb is exploded two Florans manage to drug the crew and imprison them in a tall tower. When they try to use a tall plant as an escape route, the Florans realise that they have come to help and are able to save the crew from what is, in actual fact, a man-eating plant.

When the stabilisers of Fireball XL5 break down, supplies to Space Station Nine are in jeopardy. The space craft goes faster than light, through the light barrier and the crew find themselves in a sea of air and are able to repair XL5 without the use of oxygen pills. Zoonie is suddenly grabbed by a giant bird but Steve is able to kill it with his ray gun. When they go back through the barrier Venus is unconscious. Rescue ships from Space City escort XL5 back to base where Venus is able to recover.

A note in the hand of an unconscious Patrol crewman leads Fireball XL5 to planet Zavia. At Space City, snow begins to fall and soon everything is frozen solid. Two icemen, Cardre and Rader, capture the crew and tell them that they plan to deflect the sun's rays using a giant reflector to destroy Earth. Steve is able to use a belt buckle to chip a staircase into the wall of their ice jail and they escape to Fireball Junior and use a missile to destroy the giant reflector and thus save Earth.

Two Fireball patrol ships, sent to investigate a strange cloud in space, explode. Soon black spaceships emerge from the cloud and land at Space City where two aliens order Commander Zero to order the crew of XL5 to land. Steve suspects that it is a trap but is forced to land. The aliens prepare to destroy XL5 as it comes in to land but suddenly they fall to the floor. Venus explains that they have the Space Disease Rystamesia so Commander Zero doesn't seem quite so brave.

James Frazer, an Earth geologist, discovers electronic rock on the planet Electron. He demands that Steve Zodiac takes it back to Earth but he refuses. Strange things happen as objects float around but the crew of XL5 cannot discover why. When they try to leave the planet, Frazer attacks with the electric rock which explodes on impact. Just when it seems Steve will be hit, Frazer begins to float. Two small Groverians appear and explain that they f-rightened away the Electrons as they feared that they would stop them taking the electric rock. Steve gets them to apologise to the Electrons and Frazer is taken back to Earth.

Robots have vanished from several planets. The only clue seems to be that Prefessor Himber, the greatest robot scientist in the universe, gave a lecture when the robots were taken. After Himber has left Space City Robert takes off in Fireball XL5. They follow him to Planet 82 where they are captured and tried by Himber for damaging an inhabitant of Robotvia. Their robot jurors find them guilty. Professor Matic is able to retune Robert and the Prosecutor Robot and after a battle with the robots, they take Himber back to Earth.

Lieutenant Ninety becomes General Ninety but things don't go very well for him. Steve Zodiac takes Jock to planet Olympus for his holiday. Once there Jock is knocked unconscious and Steve falls in a quagmire. Gene ral Ninety orders all patrol ships to intercept an invasion fleet in Sector 23 but it turns out to be a meteorite. Steve, saved by Jock, is told to land XL5 on Landing Pad 1, along with Freighter A14, but a tanker is taking off from it as well and XL5 crashes into Space City and other ships explode in flames. As Space City burns, Lieutenant Ninety wakes up and discovers it was all a horrible nightmare.

Venus is returning to Space City aboard one of the new supersonic airliners with General Rossiter. Major Todd, the pilot, has been brainwashed by the Subterrains and tries to crash the airliner. Steve and Professor Matic in Fireball Junior manage to talk Venus down and she is able to land the airliner safely. Back at Space City Steve is given his award as Astronaut of the Year and Venus and Professor Matic are given special awards for their bravery

Balls of fire are falling all over Earth from a gas cloud in Space. The crew of Fireball XL5 plan to enclose it in a giant satellite and, by injecting oxygen into it, letting it burn out. With time running out the crew succes sfully manage to enclose the cloud but when they try to release the oxygen nothing happens. If the container enters the atmosphere Earth will become a giant fireball. Steve, using his thruster pack, is just able to release the oxygen from outside the container and get away before it explodes, leaving space clear again.