What if the multiverse exists? What happens when dimensions suddenly collide? What do you do when you find copies of you from alternate universes walking around the streets? Or living in your house? Which version of you is "real"?

In a small town called Trosa lives a 14-year-old girl, Kori Stone, who, along with her friends-Arno, the 12-year-old boy from Ethiopia adopted by a local couple, and Edith, the 14-year-old daughter of a hairdresser-will unveil the truth. But in their quest for answers, they will face a dreadful monster and visit mysterious places they never imagined could exist.

Kori lives with her parents in a Swedish town not far from Stockholm. One evening, everything changes when her neighbor, Rosemary-a 59-year-old widow-knocks on the door and tells Kori and her mother that she has found a body in her backyard. Together, they go over to check if Rosemary is telling the truth. On the cold grass, they see the body. It's female. And it's Rosemary. In shock, they return to the house only to find another Rosemary there, alive and well.

On that October evening, many inhabitants of Trosa experience the same thing. Endless copies of themselves appear everywhere, dead or alive, seemingly out of thin air. They look similar, but they are not the same. What is happening? Is it a virus? A curse? Or... a new kind of reality?

And it's not just the copies that are strange: Trosa has become an island, surrounded by white, sticky water. There's no communication with the outside world-if it even still exists. Kori's mother, Arina, remembers that her grandmother-a powerful medium-predicted that situation, and she had left a magical belt for her granddaughter.

With the help of that magical belt, the kids arrive at the top of the mystical mountain Yah-Weh, 6,000 kilometers underwater, surrounding their little town. They don't expect to meet a monster there-the all-seeing-eye who calls himself "Popa Bowa." It seems he was waiting for them...

He proposes a bargain: he'll save Trosa and the colliding worlds from collapsing and stop the constant arrival of copies if the kids bring him something from each realm hidden behind three magical doors. The first door is golden- the land of Ahora, where Fire Centaurs live-and the monster asks them to bring him something that is most hated there.

If they don't do what he asks, it will cost them and the world dearly...