Maria Wern 9 Not even the past

Summary

The old wooden door to the prison tower Kajsarn in Visby is slightly open. The boy takes the girls hand in the dark when the moist, cold air hits them as a breath from death and the door closes behind them. No one would be able to hear their call for help.
They stumble not to fall down in the dark cave. Between the rocks in the wall Erik finds a leather pouch with a map. In the dim light from the lighter they see it is dated 1816. Since that night, they have a secret agreement - one day they shall go to Gotska Sandön and dig up the shipwreck looter's treasure.
After thirty years of waiting and just as a possibility to collect the treasure opens up, everything is shattered. Just before Christmas, Erik Hansson is found frozen to death in his car on highway 142. There is no proof of a crime. In a confused state, thoughts of revenge and death for a lost life rise. The ones that have caused so much pain and shame shall not remain unpunished.
Death writes an invitation. Seven women travel to Gotska Sandön for a rehab camp, paid for by the Social Insurance Bureau. There is a storm and all the electricity is cut off. Only a few of them will return ...
One of the women on the island is Maria Wern. She needs to disappear for a while since she is going to testify in a trial and has received death threats. The trip turns out to be a fatal mistake: after a couple of days she realizes with horrific clarity that they are all included in an evil plan.