Barber-surgeon Johan Gustav Daadh returns to Stockholm from the war in Finland. He's taking a patient, Simon Freund, to chief constable Wahlstedt's home, where Freund has been working as a tutor. But there Daadh's life takes an unexpected turn. For one thing, he falls head over heels in love... with the chief constable's wife Magdalena. And he also becomes involved in solving a murder case, which he does so successfully that, to his surprise, he is offered the position of district commissioner, i.e. police inspector. Daadh's first reaction is to turn it down, since he's a political radical and objects to the injustices in society. But when he realises that Magdalena believes in him, he decides to accept the job, with Simon Freund as his assistant. Johan Gustav Daadh's intention is to use his new position of power to try and make a difference... in the name of justice.
A shop owner is found dead with a knife in his chest. A man has been caught seemingly red handed, but Daadh is not satisfied with what seems to be the obvious solution, and instead tackles the problem from a completely different angle and reaches a surprising conclusion. One of Daadh's radical friends from the old days needs his protection, but their meeting ends in tragedy that suddenly makes Daadh the focus of a vengeful woman's rage.
Libellous pamphlets against the king are being distributed around town. When Daadh is going to interrogate the person who printed them, the man is found murdered, his skull crushed in his own printing press. Daadh's investigation brings him in contact with a beautiful and radical young French woman, and, after a few more gruesome murders are committed, Daadh realises that the old adage holds true hell hath no greater fury than a woman scorned. This is just as true of Marta Raxelius, who is convinced that Daadh killed her brother and will stop at nothing to get her revenge.
A cunning burglar is wreaking havoc in Stockholm. As the panic spreads, Daadh is under great pressure to apprehend this masked thief, who is known to be both dangerous and violent. He is close to getting caught, but escapes, whereupon Daadh is offered help from the renowned hypnotist Cagliostori, who happens to be performing in the city. Daadh allows himself to be hypnotised, falls asleep and wakes up in a most unpleasant situation where his very life is in danger.
A bomb explodes in one of Stockholm's packed coffee houses. Daadh's investigation of the attack is interrupted by an order for him to put a stop to the illegal church services held by a pietistic congregation - of which Simon Freund is secretly a member. No sooner has Daadh taken care of this crisis - in his own manner - then suddenly another murder takes place that demands his attention. A respected priest in the state church is found burned to death. Daadh starts to sense that there is an unexpected link between the two murders, and that the perpetrator could be found in unsettlingly close proximity...
One of Daadh's old radical comrades is accused of treason and hung on the square. His body is going to be donated to Uppsala University to undergo dissection for the advancement of medical science. But the body instantly disappears, and the two students who were sent to take possession of it are found murdered. Daadh soon realises that his enemy Marta Raxelius must be involved in the theft of the body. But two more murders take place, and it becomes clear to Daadh that someone is ready to kill indiscriminately in order to prevent him from uncovering the dangerous truth he has got wind of. And before he realises it, his own life is also in danger.
A number of children are found dead in the great piles of excrement and rubbish that line Stockholm's shoreline. Daadh's investigation leads him to the Great Orphanage, but there they claim to know nothing about the bodies. One of the children from the Orphanage is chosen to carry out the drawing in the Number Lottery, a popular event where large amounts of money are in play. And to Daadh's dismay and anger he is forced to concede that a child's life is worth little when money is at stake.
A landowner is found dead in the stables of his estate, kicked to death by his horse. Daadh soon determines that the tragic accident was actually a murder. He has no difficulty finding people who bore grudges against the victim, but is unable to tie any of them to the crime. Any member of the victim's family could have done it, but the evidence is very scanty. Then the chief constable intervenes and decides that the law must run its full course someone has to be found guilty!
Daadh is invited up to Uppsala by his old professor, who needs his help to find out who poisoned one of his students. Daadh involves himself in the case and quickly realises that his own life is in danger. Someone clearly doesn't like him snooping around. Meanwhile, subversive events take place at the home of chief constable back in Stockholm that will affect Daadh's future. And furthermore, his old enemy Marta Raxelius has decided to put her planned revenge into action but rather than striking at Daadh, the blow lands on someone else altogether.
Daadh's world has been shaken to its foundations. His friend Freund has disappeared and Daadh's worst enemy has taken the deathly ill chief constable's place. Through his knowledge of medicine, his courage and his ability to see patterns in seemingly unrelated events, Daadh succeeds in turning the situation around, and even uncovers a crime ring with connections to the highest levels of society. But suddenly he is harshly confronted by his own past and is forced to bargain with those in power in order to save his life. This experience causes him, for the first time, to seriously question his future as an officer of the law.