Investigating the death of his cleaning lady's nephew, Coliandro uncovers an extreme fighting ring involving a series of wrestlers who are systematically drugged to relieve pain and fatigue. Helping him unravel the case is Veena, a beautiful and athletic fighter who escaped from this group of modern-day gladiators.

Coliandro believes that Gamberini has relapsed into the old habit of gambling and, trying to help his friend, infiltrates a clandestine gambling ring. In doing so, however, he blows up an investigation already underway promoted by Longhi and puts Giacomino, who he has hired as a consultant, Gamberini and himself in grave danger. Thanks to the help of Ambra, the girlfriend of one of the criminals, the inspector still manages to get away.

Coliandro is contacted by a girl who needs help: her boyfriend disappeared after stealing a smartphone and finding footage of a gang of Russian criminals inside. The young woman turns to the inspector because she often hears him mentioned by her aunt, the deputy prosecutor Longhi, who however believes that Coliandro is not a good policeman.

Kayo, a young Japanese doctoral student in art history, is an involuntary witness of a ruthless execution. She casually runs into Coliandro, who decides to protect her and hide her at her house with Kenzaburo, her brother. The man, who arrived from Japan in defense of his sister, is a former repentant of the yakuza, the fearsome Japanese mafia, which is hunting them.

Coliandro seems to be on the verge of positively concluding a gallant adventure. But, at the climax, Giacomino shows up at his house, sleepy, hungry and with handcuffs on his wrists. The motivation is incredible: Giacomino is accused of being the author of a series of brutal murders. To help his friend, Coliandro will have to hunt down the real serial killer.

Coliandro is forced to be Paffoni's dance partner for one evening. To escape the thankless task, he finds himself investigating the murder of a young singer. To help him there is not only Paffoni, an experienced dancer, but also Natascia, the new young and beautiful singer of the smooth orchestra led by the shady Vasinto and his wife Ersilia called "Vagona".

At the Questura Coliandro meets Asmareth, a young and beautiful Eritrean cultural mediator who works for the police. Believing her to be an illegal immigrant, Coliandro puts together one gaffe after another. To make up for it, he agrees to help her in a research that the girl is doing on illegal work. Coliandro and Asmareth thus unmask a gang that organizes "manhunts" for bored provincial rich people.

Aurora, the beautiful and intelligent daughter of De Zan, falls in love with Coliandro. When the man wakes up from his coma, he finds the Inspector invited to his house for dinner. Meanwhile, the team investigates a mysterious man, Salvatore Maria Moneta, known as "the Ghost" who, thanks to his quick-change skills, always manages to escape the handcuffs.

Coliandro meets Thea, an ironic and provocative investigative reporter who, together with "Cinno", a young hacker, is investigating the affairs of Roman Kolas, an Uzbek entrepreneur who conducts very shady business under the facade of philanthropy.

Coliandro comes across Francesca Maria, the elegant and refined curator of a museum able, with her seductive qualities, to always get what she wants. Dazzled by the woman, the Inspector has to face Masino, an unscrupulous art dealer with a disturbed personality.

Coliandro investigates together with Jamila, a young and brilliant agent of the French services, on Tarantola, an apparently perfect policeman who, through the fixer "Don Lurio", is the terminal of a gang of corrupt agents.