In the year 2025, global warming has caused the polar ice caps to melt and the sea to rise, flooding large swathes of land on Earth. Richard and Amy Webber, members of underground environmental pressure group Greenwatch, teach science at a school on Black Combe Island in the Western String of the Cumbrian Sea, hoping to raise a new generation of physicists that can fix the planet. Amy discovers that two of her students, Mai-Li and Ash, possess advanced, genetically-engineered telepathic and telekinetic abilities like hers, with the former able to 'flip', turning a tennis ball inside out. However, she is also concerned for their safety in the face of ruthless federal government task force The Commission and its telepath agent Kurt Glemser, who have taken away others of their kind.

Richard and Amy are arrested in a raid on the school dictated by The Commission and Glemser, leaving their own children, Greg and Karen, to fend for themselves. They join Ash and Mai-Li to find Goodman, an old associate of the Webbers, at his laboratory within a derelict mill. Goodman becomes their guardian and recounts the history of Greenwatch, explaining to them how its outlawed scientists have been blamed by the government for causing the disaster they had tried to prevent, but soon falls sick from his underlying illness. The children have to return to the raided school with caution and trepidation, attempting to find medicine to treat him.

Back at The Commission's headquarters, Glemser forcibly interrogates an imprisoned Amy in a malevolent attempt to locate and arrest the missing 'sender' children. Amy tries to send a warning message to Mai-Li for them to escape through her own telepathic abilities, but she is too late; eventually realising that herself and Ash are in imminent danger, Mai-Li is then faced with hacking into Goodman's mind and altering his memories before Glemser forces him to betray her too.

Goodman is requested to treat an aggressive Japanese leaf worm disease that has apparently broken out on a farm, affecting its crops. After the group arrive, it transpires that the unscrupulous owner of the farm, Harry Fellside, is using illegal, highly toxic nerve agent chemicals to promote the growth of his plants, and ruthlessly forcing his captured 'climeys' (climate refugees) that have fled from a similarly-flooded France into brutal lives of slave labour exploitation.

The children pick up a sudden nearby distress signal from the small Loppergarth Island on their boat. Responding to the call, they sail out to find its village completely deserted with no apparent population living there, save for Gemma, a disturbed, sleep-deprived ten-year-old girl who is constantly running around the streets and erratically scrawling a strange, recurring anarchy symbol-like drawing, following one whole week of compulsively attempting to keep herself awake.

Having run out of fuel while at sea, the children are given no choice but to moor their boat on the nearest possible island. While there, they discover space dedicated to parts of the time before the floods, looked after by a strange middle-aged woman with an electric eye socket named Polly Phemus. Upon trying out her virtual reality video games, it becomes clear she is attempting to trap them, and the group strive to break out of the virtual world and get back to real life.

In need of an old car part to power Goodman's broken electricity generator, Ash and Greg travel to the Cartmel scrap market, where goods are now bought by civilians in exchange for euros or bartering items of value with each other. The boys find the part available for sale, however its owner demands an unviable return. They instead decide to try their luck at Devil's Island, a mound of land largely consisting of a giant scrapyard with a dangerous reputation. While looking around the deserted site, they discover that it is inhabited by numerous feral, mutant dog-like children of varying morality, living as a pack among the vast waste.

Joshua, a young 'sender' who has been arrested by The Commission, appears to go missing while under their authorised escort transference. Now a fugitive seemingly looking for help from the children, it is eventually revealed that the boy and the Greenwatch personal computer have been programmed with a life-threatening psychic virus by Dr. Galina Renkova, developed by her with malicious intent to make the telepaths progressively attack and destroy one another.

Greg sets off to replenish the group's supplies of a vital plant ingredient needed for sunblock, essential in the new climate. During his search trip, he meets a mysterious, attractive brunette, Siren, who appears to have the plant he needs. Through her, Greg finds himself caught up in the sinister activities of a strange sun-worshipping cult, who are determined to put a stop to people they perceive to be 'interfering' with nature and what is seen to be its natural course.

Greg takes a bored Mai-Li and Ash on a boat tour around the nearby islands to avoid staying cooped up indoors. They subsequently receive a morse code message from Paradise Island. Heading there, they discover and attempt to help old island resident Hepzibah McKinley, a scientist who claims to have discovered the secret of cold fusion, and is continuing her father's incomplete research into the subject to try and create greater sources of energy for the remnants of the world.

Greg and Mai-Li investigate an empty dinghy, drifting away in the sea. Suddenly drugged and kidnapped, Greg wakes up in a house with no memory of the prior events, and a young girl, Marianne, tells him that he was found floating alone. Unbeknownst to Greg while he is looked after, her father, Professor Peterson, plots to experiment with and ultimately sacrifice a captive Mai-Li in an attempt to cure his daughter of the rapid-ageing condition that she is actually suffering from.

Goodman takes Ash to the Cartmel scrap market for video spares. While there, he meets Luke, a fellow 'sender', and is lured to fall in with Skylar, a Fagin-like crook who convinces senders to steal for him. In return, Skylar provides them with 'tags', dangerous chemical strip patches that stimulate and enhance their special abilities at the risk of serious side effects. Ash becomes addicted to these, concerning his friends and coming perilously close to burnout and health complications.

Amy appears to escape from The Commission's headquarters, and in an attempt to be reunited with her colleagues and family makes her way back to their base. However, she starts to show more unusual concern for the current whereabouts of the two 'senders', instead of her own children.