A few minutes before the premiere, a prima ballerina died suddenly in her acting room. There are a few injection marks on the arm. In the locker is a syringe and a bottle of heroin. Yeah, she was a drug addict. But death came from the introduction of a solution of too strong concentration. Where did he come from? Who gave her this lethal ampoule? Is this a mistake or a premeditated murder? A police investigation begins, which leads to respectable and good people supplying drugs to Czechoslovakia.