1917. On a battlefield near the River Aisne, John lies in the aftermath of a blast, unable to move or feel his legs. Struggling to focus his thoughts, he is lost to memory--a chance encounter in a pub by a railway, a hot bath with his lover on a winter night, his childhood on a faraway coast--as the snow falls. 1920. John has returned from war to North Yorkshire, near another river--alive, but not whole. Reunited with Helena, an artist, he reopens his photography business and endeavours to keep on living. But the past erupts insistently into the present, as ghosts begin to surface in his pictures: ghosts whose messages he cannot understand. So begins a narrative that spans four generations, moments of connection and consequence igniting and re-igniting as the century unfolds. In luminous moments of desire, comprehension, longing, and transcendence, the sparks fly upward, working their transformations decades later. This resonance through time--not only of actions but also of feelings and perceptions--desire in its many forms--are at the heart of this novel's profound investigation.