On an otherwise ordinary day in the coastal town of Werrinup, Ben discovers in quick succession that there is a portal to a parallel universe in an old drain, he has a sister, his mother is a Guardian of the Parallax, his best friend has a sneak thief double from another world and these large flying purple insect things (Welkin) want to bite him.

Together, Ben and Katherine just manage to fight off a welkin attack, though Ben has yet to master the Stave which he's 'borrowed' from Veronica. They both want answers to their mother's role as Guardian and the mysteries of their separate worlds, but when Katherine confronts Veronica, her mother is evasive. In Katherine's World, Ben stops repossession of Katherine's home by smuggling in a valuable heritage artefact.

Ben follows Francis (thief) into the third parallel universe where hippies and tie-dye are the rage. There they work out an arrangement. He and the two Francises work out a scam to pay back Ben's Martin. Veronica works with Katherine and her friend Melinda to recover the Stave.

Ben organises a rock'n'roll dance. Katherine brings Stefan, hoping to reunite him with Veronica. The night is a success thanks to Francis (thief).

Katherine's Melinda goes exploring in Ben's world. Melinda and Florence the Chicken find a new portal that leads to a Hi-Tech rubbish tip. The kids arrive to rescue her and are attacked by Welkin and Ben is bitten.

Katherine and Ben play an inter-world version of pass the parcel as they each try to off-load Francis (thief's) loot from the futuristic rubbish tip. They are almost caught and their inter-Parallax travels exposed, but Veronica saves the day. Francis (thief) discovers theTechno Town version of Werrinup and Una, the girl of his dreams.

Ben discovers that by pressing the points of the portal sign he can travel to a distant new world. He meets Mundi and is introduced to a town where people live in the treetops of a forest . Its fun until he is scratched in a Krellick attack. Veronica, in disguise as a New York art dealer, turns Stefan's exhibition into a success.

Ben is sick as a result of the Krellick scratch. His friends travel to Forest World to get the antidote but wind up in a huge battle against the Krellicks. They are losing when Veronica arrives to save the day - and ask pointedly just how many kids are using the supposedly 'secret' portals.

Katherine and Ben are sent on individual quests. Ben visits Desert World and has to use his head after his rash actions land him in strife. Katherine is sent to Forest World, where a night of singing and dancing teaches her to open up her emotions and that not everything of value has to be ""logical"".

Tired of the Martins giving them a hard time, Ben and the gang get their revenge. They lure the Martin from each of their four worlds to Forest World and force them to confront each other. The Martins are terrified when their ""reflections"" talk back.

Veronica reveals that Betti is her twin sister, and that the Welkin and Krellicks are part of Betti's army, sent to destroy the remaining Guardians to prevent them interfering with her plans to blandish the Parallax. She also tells Ben that Stefan, not Jeremy, is his real father. An angry and disillusioned Ben refuses to follow her to the refuge in Forest World.

To distract Betti from her search for the newly-found Guardian, Veronica sets herself up as a decoy in Techno World. Ben and Katherine arrive in time to see Veronica disappear in front of Betti in a blinding purple flash.

Jeremy convinces Ben that Veronica must still be alive and that Ben can find her. Ben sets off after Spy Boy in Techno World, but is lured into a trap. Katherine arrives in time to rescue him, but it turns out Ben has also accidentally led his local Tiffany to Forest World, and she doesn't want to leave.

Betti disguises herself as Veronica and goes to Ben's world, determined to find the mystery male Guardian, but Jeremy, the kids and Mrs Dawes fool her. Ben and Mundi find another Portal in Forest World, along with the missing Guardian's Stave.

Ben recruits Jeremy and Stefan to help fight Betti, but the two dads immediately lock horns the moment they meet each other. Ben discovers that the Staves can act as intercoms, and that Veronica is still alive.

Betti lures the gang to Techno World. The kids, assisted by Jeremy and Stefan, fight the Krellicks and win the battle. But Betti wins the war when she and Spy Boy blandish the world. Katherine fools Betti into thinking that Ben has been eaten by the Mother of all Welkin.

Ben and Katherine find Otto, the lost Guardian of Forest World. Otto reveals that Veronica's pots are a map to the Reading Room of the Parallax. Katherine reveals her existence to Betti.

Ben finds Otto in Techno World, but they are tracked by Spy Boy. Katherine speaks to Betti and tells Veronica, in code, that Ben is still alive. Otto tells Ben the purpose of the Reading Room.

Stefan and Jeremy are determined to take the initiative - and promptly lose themselves, and Tiffany, in the Parallax. They blunder into Betti relaxing in Desert World and only escape with Katherine's assistance. In the confrontation Betti finds out more about both Ben and Katherine and is on their trail.

The two Martins want to know everything about the Parallax. Betti buttonholes Katherine's Martin - the greediest - and, shows him the possibilities of a Parallax that includes Techno World in return for information about Katherine.

Betti finally gets her meeting with Katherine and proudly shows her intended 'partner' around ""Garden World"" as an example of how people live happily and prosper in a blandished world. For a moment Katherine thinks that Betti may actually have a logical point - but she soon realises that Betti's perfect worlds come at a great cost.

Betti recruits the Martins from the various worlds to help her track down Katherine. Betti discovers Ben is still alive. Katherine and Ben find out that the Orb made the Guardian's Hut a sanctuary, but are forced to leave Forest World to avoid Betti.

Ben and Katherine find another Orb in Ben's world, which transports them to the Reading Room. They view the different worlds and find Veronica imprisoned in Garden World. Francis Surfer volunteers to go and rescue her.

Betti sets a trap for Ben and Katherine at the Garden World portals. Francis Surfer finds Veronica, and helped by Spy Boy and Otto, the gang manages to get home safely. A furious Betti destroys Ben's home..

Ben and Katherine outsmart Betti and trap her in Desert World, but have to return to rescue Katherine's Martin. Katherine blandishes Betti. Veronica and Otto work out how to revive all the people in the Parallax who have been blandished, including - unfortunately - Betti.