After the horror of World War I, Tom Sherbourne welcomes his new job as the lighthouse keeper on Janus Rock, an isolated island with no residents aside from him and his wife Isabel. But times on the island are tough for Isabel as she suffers multiple miscarriages and a stillbirth in just four years time. When a boat with a dead man and a young baby washes ashore, Isabel convinces Tom to let her keep the baby as their own, but the consequences to her actions may be dire.