Army surgeon Johan Gustav Dåådh gets offered the job of district police commissioner as he's seeing a patient home in Stockholm. He's also fallen in love with the chief constable's wife, Magdalena. When he realizes that Magdalena believes in him, he accepts the position and takes on his former patient, Simon Freund, as his assistant.
A shop owner is found dead with a knife in his chest. A man has been caught seemingly red-handed, but Dåådh is not satisfied with what seems to be the obvious solution. He approaches the investigation from a different angle and reaches a surprising conclusion. One of his radical friends from the old days needs his protection, but their meeting suddenly makes Dåådh the focus of a vengeful woman's rage.
When Dåådh goes to interrogate the person who printed pamphlets libeling the king, he finds the man murdered, his skull crushed in his own printing press. Dåådh's investigation brings him in contact with a radical young French woman and with Marta Raxelius, who's convinced that Dåådh killed her brother and will stop at nothing to get her revenge.
A cunning burglar is wreaking havoc in Stockholm. As the panic spreads, Dåådh is under pressure to apprehend the masked thief, who's known to be dangerous and violent. He's offered help by the renowned hypnotist Cagliostori, who happens to be performing in the city Dåådh allows himself to be hypnotized, unwittingly putting his own life in danger.
A bomb explodes in one of Stockholm's packed coffee houses. Dåådh's investigation is interrupted by an order for him to put a stop to the illegal church services held by a pietistic congregation -- of which Simo Freund is secretly a member. When a respected priest in the state church is found burned to death, Dåådh suspects there's a link between the two murders, and that the perpetrator could be found in unsettlingly close proximity.
One of Dåådh's old radical comrades is accused of treason and hung on the square. His body is to go to Uppsala University for dissection for the advancement of medical science. When the body disappears and two more murders take place, Dåådh realizes that someone will kill indiscriminately to prevent him from uncovering a dangerous truth.
A number of children are found dead in the great piles of excrement and rubbish that line Stockholm's shoreline. Dåådh's investigation leads him to the Great Orphanage but there they claim to know nothing about the bodies. Each year, one of the orphans is chosen to carry out the drawing in the Number Lottery a popular event where large amounts of money are in play
A landowner is found dead in the stables of his estate, kicked to death by his horse. After Dåådh determines that the accident was actually a murder, he has no difficulty finding people who bore grudges against the victim. Any member of the victim's family could have done it, but the evidence is scanty and the chief constable is demanding hat someone be found guilty.
Dåådh is invited up to Uppsala by his former professor,who needs his help to find out who poisoned one of his students. Dåådh involves himself in the case and quickly realizes his own life is in danger. Meanwhile, subversive events take place at the home of the chief constable back in Stockholm that will affect his future.
With friends gone and his worst enemy closing in on him, Dåådh's world has been shaken to its foundations. Through his knowledge of medicine, his courage and his ability to see patters in seemingly unrelated events, Dåådh succeeds in using the challenging circumstances to his benefit. But he is also harshly confronted by his own past and forced to bargain with those in power.