For private detective Tatyana Ivanova, things are not easy. But this... For several days, forgetting to have a snack, having almost no time to take a nap, she rushes around the city in search of the only person who could poison the famous businesswoman Inna Rossova. But who is he? How did you get to the presentation at her luxurious mansion? And for what reasons did you commit murder? Having found out his name with great difficulty, Tanya understands: he has no motive for the crime. But then who poured cyanide into the fatal glass of champagne? In the end, Tatyana finds both the reason and the culprit, but... lets the killer go free! And again follows on his heels...