Hannah is a fusion scientist working alone at a remote cottage off the coast of Scotland when she sees a figure making his way from the sea. It is a visitor from the future, a young man from a human settlement on Mars, traveling backwards through time to try to make a crucial intervention in the fate of our dying planet. Roban lives in the Colony, one of the first generation born to this sterile new outpost, where he is consumed by longing for the lost wonders of a home planet he never knew. Between Hannah and Roban, two generations, a father and a daughter, face a world that is falling apart. Andrew believes there is still time for the human spirit to triumph. For his starkly rationalist daughter Kenzie, this idealism doesn’t keep the rising floods at bay. She signs on to work for a company that would abandon Earth for the promise of a world beyond --- in contravention of all Andrew stands for.

Sol and Liz are a couple on the cusp. He’s a professional cyclist in the Tour de France, a workhorse but not yet a star. She’s a geneticist on the brink of a major discovery, either that or a loss of funding. They’ve just welcomed their first child into the world, and their bright future lies just before them --- if only they can reach out and grab it. But as Liz’s research slows, as Sol starts doping, their dreams grow murkier and the risks graver. Over the whirlwind course of the Tour, they enter the orbit of an extraordinary cast of conmen and aspirants, who draw the young family ineluctably into the depths of an illegal drug smuggling operation.