On 13 December (St Lucy's Day), a bandit daringly robs a crowded post office. Within a fortnight, two witnesses are dead. Vice cops Johansson and Jarnebring, the first to the scene of the crime, pursue all leads and identify a suspect, an arrogant member of the elite secret police, assigned to guard the country's Minister of Justice. Just as they think they've tightened the noose around the suspect, loose ends appear, witnesses lose certainty, alibis arise, and even the cops doubt what they've seen. Who's protecting the suspect and why?