It is 1918, and having survived the horrors of the First World War, Tom Sherbourne enlists as a lighthouse keeper on remote Janus Rock, the last point of land where two oceans diverge. Thawed by the seclusion and ritual of this life, Tom meets and falls in love with his wife Isabel on a trip to the mainland. The two return to the lighthouse and begin an intimate and almost sacred homemaking. But when Isabel suffers multiple miscarriages, the island’s seclusion starts to feel precarious and haunted. Until a day comes when a boat carrying a dead man and a screaming baby washes up on the shore. Isabel and Tom make a decision that enters them into that gray area when there is no clear right or wrong. The ripple effect of this decision becomes a pulsing force, and ultimately the novel questions life, the beauty and ugliness of it, the light and dark of it, and the shades in between.