DCI Carl Morck returns to work after a near-fatal incident and finds himself head of a new department. A prosecutor faces a tough day in court.

As Carl and his new assistant start digging into their first cold case, he can't stop his personal demons encroaching on his professional life.

The police detain a suspect for the Leith Park shooting. Carl returns to the scene of the crime, before losing his temper in public once again.

Carl makes some dangerous allegations to some powerful men, while Rose takes a fresh angle to uncover more information about Sam Haig.

The kidnappers give their victim a clue as they press her for an answer to their question. Dept. Q gets closer to unravelling its own riddle.

A decades-old recording helps all the clues to fall into place. But as the pressure rises — in and out of the chamber — can Carl get there in time?