There came an elastic aftershock of creaks and groans and then, softly softly, a chinking shower of rubbled cement. Leaves calmed and trunks stood serene. Where, not a minute before, there had been a suburb, there was now only woodland standing amid ruins There is no warning. No chance to prepare.

They arrive in the night: thundering up through the ground, beating at the air with their branches, transforming streets and towns into shadowy forest.

Buildings are destroyed and power lines felled. Broken bodies, still wrapped in tattered bed linen, hang among the twitching leaves. Something creeps and whispers overhead. A wolf begins to howl Adrien Thomas has never been much of a hero. But when it becomes clear that no help is coming, he has little choice but to venture out into this unrecognisable world. The trees reach to the horizon, seemingly the work of centuries rather than hours. But Adrien's wife Michelle is across the sea in Ireland and he has no way of knowing whether she is alive or dead and whether the trees have come for her too.

When Adrien meets Hannah - a woman who sees the arrival of the trees as a sign of renewal rather than destruction - and Seb, her teenage son, they persuade him to join them. Together, they pack up what remains of their lives and set out to find Hannah's forester brother, to reunite Adrien with his wife - and to discover just how deep the forest goes.

Their journey through the trees will take them into unimaginable territory: to a place of terrible beauty and violence, of deadly enemies and unexpected allies, to the dark heart of nature and the darkness inside themselves.