Museum worker Varvara Popova lost her 22-year-old son Misha. She wants the Beagle Agency to keep him under surveillance. It soon turns out that Misha simply fell in love. The object of his passion was a certain Olga Burlakova, 28 years old, the widow of the famous antique dealer Viktor Burlakov, who was killed in his apartment a month and a half ago. Varvara Dmitrievna demands that Rostovtsev find incriminating evidence on Olga. She is sure that this woman, whom her son contacted, is involved in the murder of her husband. Varvara Dmitrievna does not yet know what shocking truth about her son she will have to hear.