It is a disastrous day for Col. Raeburn when Tyro, the leader of the planet Neptune, persuades Raeburn’s secretary, Marla, to go to Neptune with him. The Colonel does not believe she has gone of her own free will and gives Dart the task of bringing her back.

When Dart and his crew make an emergency landing on Titan to repair their galasphere, they make a curious and far-reaching discovery.

Dart and Slim are invited to the planet of Lumen. On their arrival Dart's oxygen cylinder is pierced. The planet's only oxygen comes from blister plants in the "cave of death". Dart and Slim must find the plants before dawn, or risk being boiled alive in the heat of the Sun

Stolen art treasures are being transported into space. Raeburn suspects that Venusian millionaire Tara is behind the thefts, but his palace is too well guarded. Professor Haggarty develops a watch that speeds up the wearer's reaction times by a factor of sixty, which enables Dart to sneak into the palace unnoticed

Husky, visiting Mars with Larry Dart, becomes invisible through an accident. This proves of great value, but Husky does not want to be invisible for ever, and there seems to be no prospect of him returning to his normal state.

One of the lakes on Jupiter is found to contain water with extraordinary properties. This is of great interest to the scientists, but from being a matter of interest the water soon turns to being a matter of deadly peril to the planet.

Galasphere 347 is in deep space. After a comet collides with the ship, Dart and his crew discover a new planet beyond the orbit of Pluto. Touching down in the dense forest, Dart and Slim meet one of the planet's giant inhabitants

The Tula Fish in the Venusian Magda Ocean are evolving at an extraordinary rate and attack fishermen. The Galasphere crew are sent to help and discover that routinely dumped building materials may be the cause of the Tula's accelerated evolution

While Dart and his crew are orbiting around Uranus, Husky sees a light on the planet which they learn is coming from the headquarters of the Duos, strange beings who inhabit the very heart of Uranus. The Duos, however, are in search of a less unpleasant atmosphere and decide to conquer Earth.

Colonel Raeburn and Haggarty are on a hunting expedition when Raeburn shoots down an object shaped like a bell. Although not a human being, the bell has a voice and proves to be very intelligent, especially when Dart is buried in a cave without food and water.

Col. Raeburn receives a message from Mars and learns that, as a result of terrible dust storms, the drought on the planet is getting worse.

No one believes Professor Zeffer when he tells them that he has picked up a message from Alpha Centauri, the nearest Star to our solar system. But when a strange being lands on Earth, it seems that the Professor’s story is not so fantastic.

Colonel Raeburn is faced with a dangerous situation when a would-be dictator sets himself up on the satellite Ganymede and begins to interfere with the sun.

The problem of dwindling supplies of Plutonite is solved when an asteroid made of the material is discovered. But before Raeburn has managed to secure the asteroid Miga, a wealthy Venusian has taken possession and intends to sell it. Raeburn reluctantly agrees to the asking price and sends Dart to complete the transaction

Professor Borra of Venus has invented a mechanical eye which can destroy any ship constructed of metal alien to Earth, Mars or Venus. The demonstration is impressive but what will happen when a Galasphere constructed from metal mined from Pluto comes within range?

Exploring the Silver Forest of Venus, Husky becomes trapped in the web of a Spirigum Spider. Haggarty manages to free him and discovers that fragments of the web act as a truth drug. Raeburn, meanwhile, is offered the formula for Kinotine, which has the ability to store heat indefinitely. Kinotine's inventor, Dr. Mason, will donate the formula but when a call is received from Kolig, head of Mars's largest chemical plant, offering the formula for sale, Raeburn suspects foul play

Haggarty invents a robot that responds to thoughts. Dart tests the range of telepathic thought in space and investigates a new planet near the Sun unaware that the Neptunians have encamped there. Only Haggarty's new robot escapes the Neptunians' hypnotic influence

To halt a virus destroying Martian vegetation, Dart is sent with a spray that is deadly to all forms of life except those native to Mars. When the spray comes into contact with a whirlwind, the chemical is rushed into space and is soon on a collision course with Earth

A strange jittering is affecting the city and other Earth locations. Haggarty discovers, by chance, that the jittering is caused by radio waves emitted by Uranus, where the Duos are once again planning an invasion

Tyrig plans to use a nerve gas to seize power on Mars. Raeburn discovers that Tyrig and his men have set up base on the Martian moon Phobos and Dart is sent to investigate. Dart and his crew are captured by Tyrig, who wants to use the Galasphere to spread the gas. Refusing to co-operate they are placed in a dungeon which slowly fills with sand

The Galasphere's Meson unit malfunctions and lands in the unexplored Tuhera jungle. Dart and Husky leave to fix the problem. When Husky fails to return, Dart follows and is captured by a giant primitive man. Husky speaks with the giant in its native language and they are set free. They return to Earth with some Martian fruit which makes hair grow—the perfect solution to Haggarty's problem

Saturn has a new leader. Riga is succeeded by his brother Simba and whilst Dart is en route to investigate, Simba launches rockets destined for Earth containing Saturnian grass seed—which absorbs oxygen and emits carbon dioxide

The Neptunians create a forcefield around the Earth containing particles with strong electromagnetic properties. The field begins disrupting electricity supplies, causing a complete blackout

The Galasphere is sent on a rain-making mission to Mars with a cargo of oxygen and hydrogen—the very ingredients escaped criminal Marog requires to complete his bomb under construction at his Phobos hideaway

Raeburn is contacted by Yria from Alpha Centauri who is seeking help to destroy an evil computer superbrain which is attempting to take over the planet Delta

On a mission to Jupiter, Slim disappears in the swamps. Raeburn orders Dart and Husky to leave but trouble with the Galasphere's primary drives gives Dart an excuse to resume the search only to find that Slim has shrunk to dwarf-like proportions