Forbes Lighthouse is a dangerous place. Twenty-year-old Molly McLaren agrees to tend the light when her father breaks his leg, so she leaves behind the city and her nursing career. Molly dreads the thought of three months as the sole inhabitant on the tiny island, nineteen nautical miles off the rugged coastline of Augusta in Western Australia.

Molly discovers she enjoys the solitude, and when a massive storm arrives bringing a life raft, Molly risks her life to save the unconscious man inside. On waking, he says he has lost his memory but as Molly nurses him back to health she wonders if he has. When the storm finally clears, Molly has fallen for the man she's nicknamed John, but still has doubts about his honesty.

The real danger arrives with two men who are searching for her mystery man. They want to kill him and anyone else who can identify them, and Molly quickly learns; on a lighthouse, there is nowhere to hide.