Under the glow of a full moon, a sadistic murder on Nordkoster Island. 25 years later, the case remains unsolved. When rookie officer Olivia Rönning becomes obsessed with the same case her father died leaving unfinished, she teams up with former detetective Tom Stilton, now disgraced and living on the streets. Their unlikely partnership brings them closer to solving the age-old case, but what they uncover has unimaginable consequences for both of them.