Mercy by Jussi Adler-Olsen

This book is full of suspense. A great read!
From the blurb;

'At first the prisoner scratches at the walls until her fingers bleed. But there is no escaping the room. With no way of mesuring time, her days, weeks, months go unrecorded. She vows not to go mad. She will not give her captors the satisfaction she will die first.'

The question is 'Why is this happening?' Gripping, it had me reading to the end to find the answer!