A group of five mountaineers are hiking and climbing in the Scottish Highlands, practising for a more dangerous ascent of the Eiger later in the year.

On the second day of their trek one of the party hears a noise. They follow the sound and chance upon an air-pipe that is sticking out of the ground. They can hear the cries of a person from beneath the earth. They start digging and soon discover an eight year old Russian girl buried in a small chamber. She is terrified, dehydrated, half-starved and can't speak a word of English.

The group decide to split up: two of them will take the quickest route back and alert the emergency services, the other three will take the girl the longer, safer way back to civilisation.

The quick route means climbing down the Devil's Drop: a three hundred metre, sheer rock face. During the descent one of the climbers falls to his death. On reaching the bottom of the cliff-face the surviving climber, Sarah, discovers that the fall was no accident: the rope had been cut. Someone killed him.

There's no time to go for help. Sarah must warn the others: she needs to let them know that they are in danger. She sets off at a run...desperate to reach them in time.

The other party are making their way as fast as they can. It is slow going with the young girl: she's exhausted, unable to communicate and going into shock. They are going as fast as her fragile physical state will allow. And they're being tracked...someone's following them from a distance...they're closing in...

Will Sarah make it in time and what can she hope to do even if she does?

Why was the Russian girl in the ground? Who put here there and why? Are they going to give her up so easily? Who else is out looking for her?

There's no easy way out. Every member of the party is going to have to fight for their lives if they want to make it out alive.

...Southern Comfort meets The Wicker Man...terrifying, uncompromising and brutally realistic: this is the ultimate British pursuit thriller.