With Coalescent Stephen Baxter begins a new trilogy, “Destiny’s Children”. Chapter 1 throws us in at the deep end, and the rest of the book fills in the details – slowly, surely – that allows us, in Chapter 52, to get back to where we started. Except that along the way everything has changed. All sorts of other realities and possibilities, both Earth-bound past and present, and giant galactic epic futures, are invoked, and wait for us.

When his father dies, George Poole returns to the family home, now empty, to put his father’s affairs in order. He starts finding things out about his family, and his ancestry, that he never knew. Baxter alternates these chapters of discovery with another story, that of Regina, a girl growing up in the Britain of the twilight of the Roman Empire, in the first part of the fifth century. Her story is engrossing, with plenty of detail and an overwhelming sense of loss pervading everything – civilisation is crumbling, certainties are disappearing, life is becoming dangerous and the towns empty and decay, as the Empire gradually descends into chaos. Baxter creates a post-holocaust world that has already happened, and makes it come alive so much that it hurts.