Cass Sawyer wakes up in the woods. She doesn't know what's happened, or why she is alone.

But she recognises where she is. The Haven. An off-grid retreat - the setting for what was meant to be the perfect family holiday.

As Cass searches her surroundings, memories begin to trickle through. Her father's erratic behaviour. Her mother's pleas that they go back to town. The Haven's unnerving, free-spirited leader. The strange girls that hung on his every word.

And a nagging feeling: that Cass has done something terribly wrong.