In St. Petersburg, an attempt is made on the well-known criminal authority, the owner of an underground casino network – Yuri Sergeev. A random passer-by unexpectedly intervenes in what is happening, who rebuffs the killer. The criminal is killed, and a passer-by, who turned out to be thirty-year-old Kirill Borzov, who recently arrived in the city from the provinces, receives an offer from Sergeyev to work in his security service. So Borzov gets into the world of excitement and vice. Every day, before the eyes of the main character, real dramas from the life of casino players and his servants are played out.