The Receda Cube is stolen from the Perplex City Academy. A guard is killed in the process. The Academy's Master, Sente Kiteway, sets up the Cube Retrieval Team (CRT) and traces the Cube to Earth. He contacts Earth directly for the first time, asking for our help - and offering a large cash reward.

Sente's elder daughter, Violet, discovers that Bernardo Holyoke has been murdered and that he might have been involved in the theft. Her search for clues leads her to the Cube-worshipping Reconstructionist cult, where she discovers that Aiko Entrescore (of the CRT) was a member. Aiko is cleared by the police.

Pietro Salk, of the Perplex City Sentinel, is contacted by an anonymous source. She calls herself The Advisor and claims to have been employed to steal the Cube, alongside Bernardo Holyoke, someone codenamed 'C' and their leader, the psychotic 'V'. Pietro is murdered before he can establish The Advisor's identity.

With the help of Violet's sister, Scarlett, Earth's Cube Hunters gain access to Pietro's secret files. They lead to an apartment in Ascendancy Point and to a name: Monica Grand. The Cube Hunters persuade Pietro's widow to meet Monica face to face - but too late. Monica has been brutally murdered by V.

Chasing a lead from Pietro's notes, Violet researches a sinister ancient society called the Third Power (with Kurt McAllister's help). It seems that the Third Power are still very active - even turning up on Earth in a dramatic helicopter stunt. Meanwhile, Scarlett heads off to chase another clue: an unmapped place named Viendenbourg.

Violet's Third Power research leads to an antique diary that she can only access if she's a published author - so the Cube Hunters start writing a book for her. On the way to Viendenbourg, Scarlett meets Allain Castille, a young man searching for the same place. After a dizzying encounter, Scarlett ends up in hospital and Allain vanishes.

Scarlett discovers that Allain was looking for his mother, Claire, who had disappeared from Viendenbourg months before. Viendenbourg, it seems, is a military research facility. Scarlett sneaks in and finds Allain, whom she helps to escape. What she doesn't realise is that Claire Castille is C, the last member of the Cube theft crew.

Kurt investigates the Third Power and has a run-in with the police. He and Violet work out that V was once a sound engineer at Hesh Records - they even find a recording he made of Monica Grand's murder. Meanwhile, Scarlett and Allain head further north to find Claire.

Violet's diary research is halted by the death of Chief Librarian Isaac Cymbalisty. The police call it suicide; Anna Heath, his best friend, calls it murder. Could it be related to the diary? Up in Anjsbourg, Scarlett and Allain finally track down Claire Castille - 'C' - who confirms that the thieves never held the Cube. But it's Kurt who finally identifies Cymbalisty's murderer. It's his own girlfriend, Miranda.

Having deceived Kurt, Miranda goes on the run. He enlists Violet's help and together they chase Miranda from town to town until she heads off into the mountains on foot. Kurt - now dangerously obsessed with hunting her down - follows her to an underground hideout and confronts Miranda in a final, fatal face-off. Violet arrives to find Kurt sitting by Miranda's body.

Following Miranda's death, Violet, Kurt, Anna and Scarlett begin to work together. They even involve Caine. Sharing their information, they start to get a clearer picture of the mystery behind the Cube theft. It seems that thefts at the Academy are not so unusual... equipment has been vanishing regularly for months now. Tracking a batch of stolen items, the conclave split up - and Anna ends up dead.

Since Anna's death, the Third Power seems to be a more and more powerful threat. They attempt to destroy the data link with Earth and successfully create a portal to transport a handful of agents to our world. But even the so-called good guys have a lethal edge to them: Scarlett kills a man, and the Academy is found to be conducting deadly experiments as they attempt to build a new Cube. Sente's involvement drives a wedge down the middle of the Kiteway family - and ends the career of Council Leader Camryn Scott. The new Leader, Nathan Earlywine, immediately restricts the data link, screening all communication for 'dangeorus or subversive' information. No more messages from the conclave, then...

The new Council Leader censors all communication between Perplex City and Earth - but that doesn't stop 'Combed Thunderclap' updating their Library of Babel website with clues as to the Cube's location. At length, an intrepid Cube Hunter puts the clues together and digs up the long-lost treasure - and the story behind the theft is revealed.