Over three years ago, a civil servant vanished after returning from a work trip to Africa. Missing, presumed dead, the man's family still want answers.

It is one of the many unsolved crimes left for Department Q, Denmark's cold case unit headed up by Detective Carl Morck.

But what Carl doesn't know is that the key to the investigation is in Copenhagen. Fifteen-year-old Marco Jameson is tough, smart and suspicious of police. Sleeping rough and hiding in the shadows is his way of life. But what is he running from - and what does he know worth killing him for?