A Soviet officer serves as a counterspy amidst enemies.

In the experimental clinic, a batch of valuable drug was stolen. Major Grigast suspects that someone from the clinic is involved in this. He entrusts this complex matter to a young investigator Mara. An investigation leads her to a distant border town in the south of the country, where the offender intended to ship the drug abroad.

A detective and a militia captain are working together investigating a murder. When their job is done, the feelings do not let them say goodbye.