Eight strangers... can any be trusted?

Grace's life has been hard.

After nursing her mother through a long battle against cancer, a battle she eventually lost, Grace has to get away. She's sacrificed her early twenties and now has a hole in her life. All her friends have moved on, gone to university or off travelling, and Grace is struggling.

A competition to win a hiking holiday catches her eye. It's just what she needs—fresh air, a long way from London, and a chance to meet other people.

She didn't expect to win, but to her surprise, she finds herself whisked away to the Scottish Highlands, together with seven strangers.

Each of those strangers seems to have a secret, and as an accident during their hike takes them to an unexplored location, those secrets start to unravel.

Some of her fellow travellers end up hurt, or worse, leaving Grace wondering if one of the others is responsible.

If so, will she be next?