The action of the book takes place in the year 1900. It’s a leap year—people in the folk tradition don’t like it; they believe it brings misfortune. According to the church calendar, February 29 is the day of Saint Cassian, and therefore the whole year is called Kasyanov.
Lykov, at the request of the Minister of Finance Witte, goes to Kyiv. There, Witte’s son-in-law, Mikhail Mering, has gotten into risky dealings. He is involved in housing construction and has taken out many loans. But in construction there’s a crisis, and Mering faces bankruptcy. Trying to outwit his creditors, he cheats with the collateral. The bank appraiser found out and wrote to the swindler’s father-in-law. Alarmed, Witte asks Lykov to find out what’s going on. The detective arrives in Kyiv and learns that the appraiser has disappeared without a trace…