An ordinary boy from a suburb of Sofia became the first undercover police officer in Bulgaria. Forced as a child by his father to steal and cheat, Martin becomes the perfect liar. This skill of his, as well as his hatred for the underworld, make him the most suitable person for a dangerous mission - to be implemented in the criminal organization of a large and influential businessman. While delving into the group's secrets and living in constant fear of being discovered, Martin falls in love with the most inappropriate of women - Djaro's friend Sunny. Just as he gains the trust of the mobsters, it turns out that the real enemies are in the police. Martin is left alone against everyone, facing difficult decisions.

After the beating of Emil Popov, Petar Tudzharov - Djaro found out that the commissar had survived. In order to save his life and business, the mob boss must look for new solutions. Undercover agent Martin is faced with a choice of whose side to go on. A new strong player will make him an unexpected offer. A scandalous explosion is followed by a brutal political assassination that will mess up everyone's plans.

After the arrest of Djaro and a serious shake-up of his position, Martin remains in the underworld as an undercover cop. This time his enemies are more and stronger. His new enemy is Ivo Andonov. After the death of his father and Sunny, he has nothing left to lose but to continue fighting crime to the end and at any cost. In order to prevent the acquittal of Petar Tudzharov, he must remain loyal as his right-hand man, but in the meantime enters into an alliance with the Kukata to fight against Ivo. The journalist Elitsa Vladeva also joins the actions against the underworld. Martin now knows that only by legal means is the fight doomed.

Six months after the recent events, Martin Hristov is officially a police officer in the GDBOP, in the department of Commissioner Emil Popov. Ivo rules the street, disguised behind a legal business. Next to him is Nia Tujarova, who has returned from New Zealand in an attempt to reconcile with her father Djaro. Djaro is in Turkey to make contact with the Turkish mafia and is involved in the restoration of an international drug channel through Bulgaria. Tragedy overtakes Kukata in his Spanish exile – he returns to Bulgaria with a plan for revenge. Martin took advantage of his desire for revenge. The two make a deal that affects the interests of Ivo, Jaro and the Turks in life and death.

Djaro is killed by Popov and someone will have to take his place. It is most natural that it should be Ivo. Undercover cop Martin is exposed and takes over Popov's old team. Now Errol - the new undercover cop - will try to take his place.