Carl Morck (Kaas) is a troubled detective who takes the fall when his partner is wounded during a routine operation. Reassigned to the newly created Department Q, a basement-bound job filing cold cases, he is allocated a new assistant, Assad (Fares), a smart young Muslim cop. Always one to go against orders, Morck throws them headlong into the mystery of a politician's disappearance (Richter) five years earlier. Believing the case to be unsolved, they embark on a dangerous journey that will uncover a shocking truth, leading to a thrilling and unforgettable climax.