In the year 2347, when Old Earth is pronounced uninhabitable, the Clarks load their family dog Hobart onto an intergalactic ark called the Dogstar to be transported to New Earth. Unfortunately, the Dogstar never arrives. All the dogs from old Earth and two confused robot pilots, Zeke and Alice are lost. But the Clark kids (and Gran) are determined to find the Dogstar and bring those dogs home. Robotics entrepreneur Bob Santino is just as determined to stop them.
Out in space, Glenn, Simone and Gran discover it's not easy finding a lost Dogstar in the battered old Valiant. Back on New Earth, at Bob Santino's heavily guarded School for the Gifted, Lincoln manages to breed a cat called Boombah that can sniff dogs across galaxies. Lincoln and Boombah are exactly what the Valiant crew need. But can they grab them right from under Bob's nose?
Pursued by Bob Santino, the Clark kids crash land the Valiant on an asteroid called Gavin where they meet Gemma an alien. She imprisons them, throws rocks at them and tries to eat Boombah. Eventually, they form a friendship and she joins the crew on their quest. Friendship is like that. You have to take the rough with the smooth.
Visiting Old Earth, the Valiant crew meets Ramon Ridley, the original inventor of the Robog. They help him back to New Earth to confront Bob Santino, the man who ripped him off! Lincoln creates a voice-box for Boombah so they can understand what he's saying. This proves to be an annoying mistake. Not surprisingly, the Dogstar remains lost.
The crew of the Valiant become embroiled in a war between two alien races; the Glurgs and the Radnoks. Gran tries to unite the warring factions by introducing them to the joys of competitive sport. It works. Trouble is, it turns out to be more dangerous than war and the Valiant crew members are right in the middle of it. On board the Dogstar, Zeke and Alice almost fly into an orange sun but are saved when Hobart unknowingly helps the robots fix the navigation system.
Bob Santino discovers that Glenn is a Planet Man fan and inserts spy ware into a Planet Man add-on which Glenn unwittingly buys. With Glenn's Planet Man doll now a homing device, it's just a matter of time before Bob Santino will locate and destroy the Valiant after retrieving Boombah, of course. Eventually, it's Glenn who saves the day for a change.
The Valiant is captured by the robot inhabitants of Ruca, a race that has done away with humans. Ruca now has a king and queen robot and slave robots called drones. The robots recognise Gran, with her robotic leg, as being almost like them. They confide in Gran and with her inside knowledge, she is able to save the kids from being exterminated. Meanwhile, Zeke decides to see what life is really like as a dog, and joins Hobart in his kennel. He discovers he actually prefers it to working with Alice.
A meteor shower shears off the nose-cone of the Valiant and Boombah floats away! He's captured by Bob Santino. The crew of the Valiant launch a rescue mission to save Boombah from his clutches. Meanwhile, Hobart gets Zeke and Alice to help him find his ID tag. Whilst they are away from the bridge, their ship almost collides with the BobCat and the Valiant. So near and yet so far!
Lincoln and Glenn are captured by a highly evolved race of dogs, from the planet Sirius II. They walk on their hind legs and speak like human beings. Meanwhile, Zeke loses his memory, and while Alice leaves him to find a lap link data cable, the Valiant finds the Dogstar. Simone tells Zeke to stay exactly where he is while she saves Lincoln and Glenn. But by the time she returns from saving her brothers, the Dogstar is gone and Zeke has no memory of ever seeing the Valiant.
The Clark kids meet Ramon Ridley again. He says he knows where the Dogstar is and directs them to Old Earth! Indeed, the Dogstar has returned to Old Earth. Zeke and Alice make the unwise decision to let the dogs out for a walk. Old Earth remains polluted and the toxic fumes practically destroy Zeke and Alice. But Hobart manages to save them, and they immediately leave. Moments later, the Valiant arrives. Once again, so near and yet so far. Ramon chooses to stay on Old Earth and begins cleaning up the planet with a broom.
When Hobart falls in love with a French Poodle, Zeke tries to prove to Alice that he too can feel such an emotion. Meanwhile, Simone falls in love with one of the human settlers on Karzol, a planet with a dangerous secret. Santino, Daina and Dino don't fall in love with anyone.
Glenn attends a Planet Man convention and after being chased by Bob, escapes with the old actor, Bud Rafferty, who played Planet Man in the TV series. Glenn struggles to understand that Bud is only an actor and not the real Planet Man, while Bud struggles to understand that he's not acting in a TV show when Bob Santino attacks the Valiant. In a sly ruse to escape being annihilated, the Valiant crew sends Bud to Bob as a hostage - dressed in a pink cat costume.
Lincoln invents a matter transporter called a Beambox to send keepsakes to their parents on Old Earth. Touched, Mark and Greta Clark send a few things back, but Bob Santino sneaks in a very nasty surprise of his own. Bob's 'gift' hatches into a terrifying monster as soon as it arrives on the Valiant. Fortunately, Gemma is very good at dealing with terrifying monsters. Equally terrifying are the twin versions of themselves that Zeke and Alice find aboard the Dogstar.
When Bob finds the Dogstar, the Clarks, thinking quickly, call the media. Bob can't destroy the Dogstar under the scrutiny of TV cameras. But Bob rewires the Dogstar navigation controls, disables Zeke and Alice, and sends the spaceship hurtling towards a sunŠ This time, Planet Man really does come to the rescue!
The Valiant lands on planet Ruca again but on this visit the crew have journeyed back in history to a time before the robots rose up to overthrow their masters. And no wonder the robots later revolted. Ruca of the past was run by some very nasty people, including a nine-year-old lunatic emperor. Amazingly, Gemma's the one who finds a way to his heart.
Zeke's belief that he is human leads him to play practical jokes on Alice. Meanwhile, Lincoln takes a brain-boosting holiday on the planet Mensa and attracts the attention of a certain Bob Santino. Invited to stay on Mensa, Lincoln is tempted until he realises he must use his powers to save the Valiant. Alice finally gets her own back on Zeke with practical jokes.
Hobart, Zeke and Alice come across Chester, a highly evolved yet tiny dog who speaks incessantly. Chester, a secret agent from the Planet Sirius II, is convinced he's in a prison ship and tries to organise a breakout with Hobart. Meanwhile Bob Santino sends the galaxy's best bounty hunter, Baba Ganoosh, to find and destroy the Valiant. Not only does Baba Ganoosh find the Valiant, he is confronted by his niece, Gemma. This could be his toughest mission ever.
Dino tries to impress his father, Bob Santino, by taking on the mantle of evilness. But somehow Dino just doesn't cut it as a villain even though he tries awfully hard, especially in the wardrobe department. Amazingly, Dino captures the crew of the Valiant. The kids elude him however and, not so amazingly, the Dogstar remains lost.
The kids are shocked to discover that Gran has a secret admirer. Glenn is especially shocked because Gran's secret admirer is none other than Bud Rafferty, the actor who played Planet Man. But it's all a clever ploy by Bob Santino, who has hired the actor to lure the kids away so he can capture Boombah. Zeke makes Alice a birthday cake when, by accident, he discovers her date of manufacture.
It sounds like the perfect toy. Enter a Dreampod, and your wildest dreams come true. Of course, there is a slight drawback; it's a ploy by Bob Santino to distract the Clark kids and get Boombah. Unfortunately, the Clark kids don't know this when they find themselves inside the Dreampod. And since the Dreampod belongs to Bob Santino, it's only fair that they return the favour.
The kids find the Dogstar, but it's been destroyed by meteors. Or so it seems. And when they return from investigating the desolate hulk, they get a cold. All except Simone who is the only one left to pilot the Valiant when it is chased by the BobCat. Could this all have been a trap set by Bob Santino? You bet it could! Meanwhile, Zeke and Alice have landed on a planet with trees. And it's been a long time since all those dogs have seen a tree!
A single pink hair is all it takes for Bob Santino to clone Boombah. Problem is the clone, called Barbara, grows to the size of a building and takes Dino as a hostage. The Clarks strike a deal with Bob and save his son. Onboard the Dogstar, Zeke the robot pilot, once again proves to his co-pilot, Alice, that he is human this time by becoming a portrait artist.
The Dogstar goes through a microwave radiation anomaly and ends up the size of a tennis ball. It arrives at New Earth where, by a stunning coincidence, it ends up inside the very Robog that belongs to Mark and Greta Clark. As Zeke says, 'Stranger things have happened,' though he can't think what. Meanwhile, a damaged Valiant crash-lands on Old Earth and the kids meet up with Ramon Ridley who is still trying to clean up the planet. This is difficult because Bob Santino has been dumping all his toxic waste on Old Earth.
Ramon Ridley finishes rejuvenating Old Earth and swears the Valiant crew to secrecy. He gives them a homing device that will attract the Dogstar and to everyone's surprise, it works! The crew return to New Earth with the Dogstar but are greeted by mass panic. Bob Santino has accidentally sent Robogs digging to the core of New Earth where they have triggered earthquakes. New Earth is about to implode. It's time to leave. But where to? The kids have to break their promise to Ramon but in return extract a promise from everyone to look after their old planet. Everyone is reunited with their pet dogs on Old Earth. But will history repeat itself? Probably, if human nature is anything to go by.