1992: Roskilde
On a school trip, a class is playing hide-and-seek.
It's innocent child's play at first.
Until they stumble on a terrifying sight they'll never forget...

Copenhagen, 30 years later:
Single mum Silje Thomsen is being sent threatening messages: a distorted
children's rhyme, and photos of herself. She fears someone is watching her from the shadows.
Scared for her safety, she reports it. Soon after, she disappears.

Detectives Naia Thulin and Mark Hess immediately discover similarities to another unsolved crime.
But it's not good news. And the clock is ticking.

A deadly rhyme has returned with a vengeance.
Can Thulin and Hess crack the code, before it claims its next victim?