1881 Autumn. In a small town, the corpse of an unknown man is discovered. The head of the detective department of the local police, Aragonov Ivan Khristoforovich, begins the investigation, and a young but promising assistant, Fyodor Mikhailovich Ignatiev, is sent to help him. During the investigation, it was established that the murdered man is the merchant Agafonov, who came from St. Petersburg with for the purpose of acquiring weaving manufactory. Investigators move to St. Petersburg and, to their great surprise, learn that the murdered man is not Agafonov. He is not identified by his wife, parents and colleagues. In reality, the merchant left to buy textiles and disappeared. The detectives return and the investigation begins all over again.