Six children leave the comfort of their homes. They are drawn to Coldharbour - an eerie wasteland of wind, rats, seagulls and rubbish tips. Emily and Freda, the twins, scuttle bright eyed and insect-like in search of the others. They find Thomas on a food tip. The gentle giant boy Walter joins them and so does Helen, who can read minds. And at the centre of it all is luminous Milo, his skin hot and bright with silver. Each of them has a unique gift, but they must learn to use their skills fast. Drawing ever closer in a maelstrom of fury is the Roar, something vast and dreadful that wants to destroy them all.

From the desolate reaches of space, the Roar has smelled the children of Earth and her hunger knows no bounds. Children from all over the world are rushing to Coldharbour. Here, Milo, a silver boy the size of cities, has emerged as the first great defender against the Roar. But where will the second generation come from? Six special children hold the key, but their strength is dwindling. Thomas is shocked by his discovery of the eerie Unearthers. The twins are drawn irresistibly to the ocean, compelled to dive deep. Walter, the giant, must face a terrifying trial of strength, while Helen, searching for the secret of the strange little girl, Jenny, enters the mind of the Roar itself. The lines for battle are drawn.

Millions huddle in Coldharbour, waiting for the huge and terrifying Roar. Milo, the silver child, is the first line of the Earth’s defence. Under his wings, Helen probes the Roar’s mind, while the twins, Emily and Freda, struggle to free the mysterious Protector. Walter’s task is the hardest of all - keeping the others alive for long enough to find a weapon to defeat the Roar. Only Thomas can release that weapon - if he can finally discover the true purpose of his remarkable gift. But a second enemy is also ranged against them. As the Roar approaches from space, her firstborn, Carnac, is crawling from the depths of the Earth. Only a small number of children, the drill-handed Unearthers, led by Tanni, stand in his way.