Ally arrives from England with her brothers to stay for a month in Africa - weeks of running wild on an unspoiled, untamed coast amid mangrove creeks, vast white sandy beaches, coral reefs and warm seas.
But on their first walk through the forest to the beach, Ally is swamped by a sense of an unseen presence close to her - of being spoken to.
The feeling increases as a local teenager, Leli enthusiastically sweeps her into the world of his village and their offshore island (Kisiri - the place of secrets).
It's the beginning of a friendship that swiftly becomes an intense, overwhelming bond between them.
Kisiri is a place of local legend, protected and feared: village youngsters dare each other to go there.
Village elders forbid it. Ally and Leli feel drawn to it, and land on its shores.
At once Ally feels again that invisible presence, a whispered voice.
But fear can change things, divide people. The bond between Ally and Leli feels unbreakable. But suddenly everything, everyone, conspires to drive a wedge between them.
She is, after all, an outsider - a visitor, no more.
Only weeks away, she will leave for England, simply walk away, never to return, how can she possibly share, or help?