Two married couples decided to play around and engage in sinful swinger fun. The pleasure turned out to be dubious, and a day later one of the unlucky swingers was killed in a hotel room. The most interesting thing is that... expert analyst Drongo is accused of murder. For him, it is now a matter of honor to find the real killer and thereby save not only his reputation, but also his freedom. There are many suspects, but Drongo is sure: there is no killer among them, but he will appear where he is least expected.