Two little girls go missing on the same day in Stockholm. Their disappearances are never explained. In time, the investigations are abandoned.

A chance discovery puts Detective Ewert Grens back on the trail five years later. His own personal trauma makes him determined to find out what happened to these children who were snatched from a supermarket and a car park and never seen again.

His search leads him into the recesses of the dark web and the discovery of a paedophile ring that can only be cracked from the inside. Grens is forced to call upon his retired partner, Piet Hoffman, the best undercover operative he knows, to try to infiltrate the group.

They will have only one chance - but are they up to the darkest challenge of their lives?