The Ice Princess by Camilla Läckberg

Returning to her hometown of Fjallbacka after the funeral of her parents, writer Erica Falck finds a community on the brink of tragedy. The death of her childhood friend, Alex, is just the beginning. Her wrists slashed, her body frozen in an ice-cold bath, it seems that she has taken her own life.

Erica conceives a book about the beautiful but remote Alex, one that will answer questions about their own shared past. While her interest grows into an obsession, local detective Patrik Hedstrom is following his own suspicions about the case. But it is only when they start working together that the truth begins to emerge about a small town with a deeply disturbing past.