Hannah is a fusion scientist working in a cottage off the coast of Scotland when she's approached by a visitor from the future, a young man from a human settlement on Mars, traveling backward through time to intervene in the fate of a warming planet.

Roban lives in the Colony, a sterile outpost of civilization, where he longs for the wonders of a home planet he never knew. Between Hannah and Roban, two generations, a father and a daughter, face down an uncertain future. Andrew believes there is still time for the human spirit to triumph. For his rationalist daughter Kenzie, such idealism is not enough to keep the rising floods at bay, so she signs on to work for a company that would abandon Earth for the promise of a world beyond.

In exploring the question "What if you could come back to the past and somehow change it with technology?" Joe Mungo Reed has written an immersive story of hope, hubris, and sacrifice in the face of a frighteningly precarious present.