When a six-year-old girl disappears and calling the police isn't an option, her desperate mother Pernilla turns to an unlikely source for help. She finds a cryptic ad online for a private investigator: "Need help, but can't contact the police?" That's where Kouplan comes in. He's an Iranian refugee living in hiding. He was forced to leave Iran after news of his and his brother's involvement with a radical newspaper hated by the regime was discovered....

On an abandoned boat, a body's lungs are filled with water, and the forensics team is sure that she drowned. But why is the boat still afloat, and why are there no traces of water on her clothes or body? The next day, a man turns up dead in his apartment, hanging from the ceiling. All signs point to suicide, but there's no furniture around to reach the high ceiling. Joona Linna begins to piece together the two mysteries, but the logistics are a mere...