Eighteen-year-old Kasper has gone through a rough time, but now he has landed his dream job at the amusement park Gröna Lund. He befriends Iris who teaches him how to terrify guests in the haunted house.

Thirty years earlier, in Stockholm of the eighties, sixteen-year-old Håkan's life changes when he meets Grim. They live and breathe music and have big plans for their death metal band. But it all comes to nothing when Grim dies. Håkan breaks up the band.

What really happened? Kasper, who is Håkan's son, tries to find out the truth. Together with Iris he delves into the myths and secrets surrounding the band, and his dad's best friend. Grim, who inexplicably died at such a young age. Who was he? And why does he appear in Kasper's dreams?