Karen Patten has experienced a lot of tragedy. Five years ago, a car crash claimed the lives of her husband, her six year old daughter Molly - and her unborn baby. A historian, Karen's spent the last several years burying her grief in her work. Her personal obessession: the century old mystery of Bittersweet. A rural town led by the domineering Deacon Haas, Bittersweet was flooded in the 1920s to make way for a reservoir. But when the residents were rehomed, 15 children had vanished. Without a trace.
When a crack in the reservoir causes Bittersweet to resurface, Karen leads an exploration team to search the town. Included in the group are Blake - Karen's cocky videographer - her faithful secretary Anne... and the married (and expecting) couple of Laurie and Dave Hunter. But the clock is ticking. The dam's due to be reflooded - in three days.
Arriving in the swamped ruins, complications immediately arise. A storm makes the muddy terrain more treacherous. And mysteries abound. Investigation of the town church reveals a torture chamber. The group uncovers a stone building that appears to be a factory - containing school desks... and a pile of eerie dolls.
The situation goes from bad to worse when Anne disappears in the night. Continuing their search, the team discovers the diary of a murdered little girl - Sarah Lukas. As Bittersweet's horrible secrets are revealed, its ghosts awaken - threatening everyone. Karen finds herself torn between leading her team to safety - or succumbing to her lingering grief for her own daughter.