Derek Norris, the uncle of 11-year-old Chris Anderson, has been missing for the last seven years. By his instructions, Uncle Derek is presumed dead. He has willed the Coach House in the village of Herbertville to Chris for any worthwhile purpose. Chris, along with friends Lynne and Samantha (Sam), enter the Coach House and immediately sense things are not normal. The most welcome signs are from Uncle Derek's inventions: a talking video screen named Theta (which displays words on her screen) and a robotic typewriter named Otto. Both Otto and Theta give Chris a pre-programmed warning from Uncle Derek, who implores Chris with the task of uncovering a terrible conspiracy taking place in Herbertville.

Duncan O'Reagan, a security agent, enters the Coach House to ask Chris, Lynne and Sam a few questions. One of them gives a false explanation to validate the will: they tell O'Reagan that they will set up a newspaper. The idea becomes practicable to the kids. As reporters, no one will suspect they are trying to uncover the details of the conspiracy. But O'Reagan is picking up details of his own. As Chris and his friends are setting up their primitive equipment, Sam and Lynne are mysteriously whisked out of the Coach House. Theta must explain to Chris that the evil Duneedon has transported the girls to a different galaxy.

Lynne and Sam find themselves on a planet in the galaxy Trialviron. The galaxy's ruler, a mystic head named Duneedon, feigns an apology for whisking them away. He tells them to enter a chamber for retransport. Instead, Lynne and Sam find themselves in The Problem Pit. To escape, they have to solve a series of word puzzles. The last puzzle, which Lynne must solve herself, seeks five verbs that mean ""Move in circular orbit.""

Lynne and Sam return unharmed to the Coach House. Together with Chris, they decide the first edition of their newspaper should tell the girls' story as a science-fiction adventure. (This, despite a note transported to the Coach House that implores them not to mention Duneedon to anyone.)While Chris is off to run an errand for the paper, a story character magically transports itself to the Coach House. Stricken with amnesia, she demands Lynne and Sam to tell her who she is.

Chris, Lynne, and Sam feel they have enough material to launch what they call The Herbertville Chronicle. As a last-minute addition, Chris introduces a history section. His reference book is

Duncan O'Reagan commends the kids for a good first edition of The Herbertville Chronicle. Later, O'Reagan slips into the Coach House, where a message is transported to him. Chris and Sam interview O'Reagan in a successful attempt to steal that message. Back at the Coach House, they learn, from both the message and their interview notes, that O'Reagan is not a security guard after all. He is, in fact, one of several agents Duneedon has employed to carry out the conspiracy.

Ann Blake, a Herbertville Town Councillor, stops by the Coach House to commend the kids on The Herbertville Chronicle. Chris and Sam look with suspicion as Councillor Blake donates a copy of The Official History of Herbetville, 3rd Edition as an aid to their historical column. A more receptive Lynne wants to join the Councillor on her daily routine. Chris spends his spare time refining an advertisement for a less-than-spectacular blender that seeks exposure in The Chronicle.Sam approaches him with what appears to be a discrepancy: Their historical article on the Edwards family was based on Early Country Travels. But in The Official History of Herbetville, 3rd Edition, the family name is Don Eden.Councillor Blake tells Lynne about the recent controversy surrounding the ownership of King's Park, a principal gathering place in Herbertville. Before they part ways, Councillor Blake invites Lynne to see the Mayor. One look and Lynne recognizes that the Mayor of Herbertville is actuall

Chris, Lynne, and Sam reconvene at the Coach House to compare and review what they already know about the conspiracy and postulate reasons. While Sam is off on an errand, Lynne and Chris encounter Merlin the Magician, who has transported into the Coach House. He tells them of the legends of King Arthur and the Knights of the Round Table. When Chris and Lynne ask for Merlin's help to reach the galaxy Trialviron, he gives them a word clue, which turns into a star. Chris and Lynne trace the star's path and disappear.

Chris and Lynne materialize in The Poet's Pocket. Operating the word organ is a friendly poet, Dr. Crystal Couplet, who speaks entirely in rhyme. All three share in haiku writing. Once Chris and Lynne explain the nature of their visit, Dr. Couplet shows them where to go: The Place of Change. Within a hodgepodge of books is The Official History of Herbertville, 1st Edition. But to reach The Place of Change, Chris and Lynne must make up a limerick.

Lynne and Chris find themselves in The Place of Change. They discover that The Official History of Herbertville, 1st Edition credits the Edwards family as one of the founding families of Herbertville. But Duneedon has circled the name ""Edwards"" and included a note: ""Change this to Eden."" Duneedon then uses his powers to trap Lynne and Chris in the book. They escape when Sam, back in the Coach House, opens to the same page in the 3rd Edition.Sam informs the others that they can have the second edition of The Herbertville Chronicle published on a real printing press, but only if they finish quickly. Chris submits a second chapter to ""The Duneedon Adventure."" Lynne offers to provide the first line of a limerick and allow readers to flesh up the rest.

The second edition of the Chronicle is printed. Its cover story is about Duncan O'Regan, with the headline asking, ""Who Is This Detective Working For?"" While distributing the paper, Lynne encounters two stage performers at King's Park. They are among several raising the need to keep the park. To this end, they are holding a special performance. Lynne joins them in rehearsing a scene from The Wizard of Oz. Later on, Lynne encounters an octagenarian man, Mr. Walker, who remembers a fire in Herbertville that burned down the manor home of the Don Edwards family. Many people who have lived under Mayor Eden question Mr. Walker's memory, but Lynne knows he is telling the truth. What they lack is proof.

The kids know Duneedon is leading a conspiracy to change the history of Herbertville, but they have very little evidence to go by. And that very little evidence is lost soon after Captain Hook materializes in the Coach House. With Chris and Sam watching from afar, Duncan O'Reagan secretly returns to the Coach House to steal Early Country Travels, the kids' only proof of the conspiracy. Before leaving, O'Reagan is surprised to see Captain Hook, who questions the contract agreement Duneedon had drawn up with O'Reagan. Will he get his fair share once the conspiracy works?

Someone leaves the cover to The Official History of Herbertville, 1st Edition for Chris and Sam. A note gives them directions to find the contents of the book (or so it seems). Lynne returns to an empty Coach House on a mission. She has been asked to deliver a speech in favor of King's Park for the Herbertville Historical Society. Theta and Otto, maintaining their posts at the Coach House, coach Lynne as she strives to put her feelings down in an organized fashion. Chris and Sam, meanwhile, follow the directions to the letter. They wind up in an abandoned factory. No contents of the book are waiting for them, but Duneedon and his agents are. Chris and Sam learn that Duneedon has forged a document about the ownership of King's Park. It is instrumental to the conspiracy.

Lynne stops by the house of Mr. Walker, who shares his memories as a soldier and as a firefighter. Councillor Ann Blake is there as well, and it is at this moment that Lynne tells the truth about Duneedon and his spectacular conspiracy.Both Lynne and Councillor Blake go to the Town Hall to compare their records with an old newspaper article that Mr. Walker supplied about the Edwards family. Chris and Sam, who have escaped from the factory, join up with them in search of the forged document Duneedon slipped into the Town Hall records.At the Town Hall, Chris and Sam uncover the document. It states that King's Park had been donated by Don Eden to the Town of Herbertville, and that after 70 years, the park would revert to any living members of the Eden family, of which Duneedon poses in his guise as the Mayor. But why does Duneedon want King's Park?

While another edition of the Chronicle is prepared for publication, the kids devise what they think will be a failsafe plan. Duneedon, in the guise of the Mayor, must attend the Herbertville Historical Society meeting, at which Lynne will give her ""Save King's Park"" speech. While the meeting takes place, Chris makes a daring return to the abandoned factory to find the original document on King's Park.At the factory, Chris relays, through walkie-talkie to Sam at the Coach House, that King's Park was donated forever to Herbertville by Don Edwards. He is about to read another document, but Duneedon, made aware of Chris's presence at the factory, kidnaps him. Duneedon reveals to Chris that King's Park has a large quantity of veronium, the source of his power back on Trialviron.

Chris sends a message to Lynne and Sam, telling them he is trapped on Trialviron's Planet of Maze. Another book character – this time the Genie from Aladdin's lamp – helps the girls to Trialviron, but not bvefore mixing up a few basic homonyms.

Lynne and Sam revisit Trialviron, paying a visit to Dr. Crystal Couplet. She provides a map to the girls to help them through the Planet of Maze. Once on the Planet of Maze, Lynne finds a note from Chris. He has attempted to escape the Maze.

Chris has discovered his missing Uncle Derek in the Planet of Maze. They return to the starting point of the Maze just moments after Lynne and Sam arrive. With the map in hand, the kids pilot their space cart through the maze, answering a succession of word and story puzzles along the way.

Everyone is back at the Coach House. Uncle Derek, rescued at last, explained that he had introduced Duneedon to the people of Herbertville as ""Mr. Don Eden."" That made it harder for Duneedon to gain control of King's Park and the quantity of veronium needed to take over the Earth.An inspector from another village has begun to arrest those involved in the conspiracy. (One of these agents is tricked into transporting himself to Trialviron.) Mr. Walker's contemporaries have turned up other old books and newspapers that prove that the Edwards family, not Eden, settled Herbertville.The conspiracy is broken in a special edition of the Chronicle, with the large headline: ""DUNEEDON – THE TRUTH.""Only one question remains: Where is Duneedon?

A defeated Duneedon returns to the Coach House. He tries one more attack on those who had exposed the conspiracy, singling out Theta and Otto, before the kids return. It is apparent Duneedon wants to give them more than congratulations. ""We will meet again,"" he says, ""and next time I will not be defeated so easily!""Duneedon escapes to Trialviron, leaving the post of Herbertville mayor empty. Councillor Ann Blake has decided to run for the job. It is the vehicle that persuades Chris, Lynne, and Sam to continue publishing The Herbertville Chronicle.