Doggerland, 6200 BC. As rivers rise, young mother Shaye follows her family to a sacred oak grove, hoping that an ancient ritual will save their way of life. London, AD 2156. In a city ravaged by the rising Thames, Shante hopes for a visa that will allow her to flee with her four-year-old son to the more prosperous north. Two mothers, more than 8,000 years apart, struggle to save their children from a bleak future as the odds stack against them. At the sacred oak grove, Shaye faces a revelation that cuts to the core of who she is; in the wilderness of the edgelands, Shante finds herself unprepared for the challenges and dangers that surround them at every turn. As Shaye and Shante desperately try to hold their families together in the face of disaster, these two young mothers uncover a terrifying truth: that it is impossible to protect the ones they love.