A successful young man, the director of a computer company, learns from his programmer friend about his unique discovery - the ability to control time using mathematical calculations. The main character conducts an experiment and finds himself in the era of Paul the First. He learns that history as we know it is not true. David decides to prevent the assassination of Emperor Paul, considering him a bearer of positive ideas in the history of Russia. A scientific experiment turns into a complicated detective story both in that time and in the present. Everything that can be changed during the time of Pavel Petrovich is reflected in the life of David and his loved ones.