The text message is just three words: I need you. Isa drops everything and heads straight to Salten. She spent the most significant days of her life at boarding school on the marshes there, days which still cast their shadow over her now. Something terrible has been found on the beach. Something which will force Isa to confront her past, together with the three best friends she hasn't seen for years, but has never forgotten ... How much can you really trust your friends?