The "principle of intervention" is a detective story, a drama, a comedy, and a funny, touching story. It tells us about Stanislava, whose only support is work. The pure cold reason, logic, and mathematics. It is her safe space, the world where she sets her own game rules and feels safe. Suddenly she gets an offer she can't reject, but she can't accept it because it is strange, illogical, and dangerous. And yet, the associate professor of the department of higher and applied mathematics becomes a cook. She spent seven days in the city of her childhood, from which she once flew out in a traffic jam and vowed never to return. At least this week's task is to infiltrate the wedding and ensure that the bride is alive, to find and punish the murderer.