Military journalist Igor Vladimirov turns to his longtime friend — intelligence colonel Sergey Matveev — for help. Fifteen years have passed since they last met. A quarrel over a woman named Zhenya, whom Igor eventually married, drove them apart. Reluctantly, Matveev agrees to let go of past grievances and visit Vladimirov at his country house.

The main character of the film, Mikhail Perov, is a professional diver. In his past, he failed to become a businessman, and in the present, he has large debts because he is a gambler. One day, he receives a strange telegram asking him to come and help his old friend, Garik Sedykh. Without hesitation, Perov sets off on a journey. His younger brother, Alexander, accompanies him. Upon arriving in a small coastal town, Mikhail learns that his friend has been murdered. Before his death, Garik, who worked as a bodyguard for the thief-in-law Pereverzev, hid a case with the thief's cash in a complex underwater labyrinth. He encrypted the coordinates of the location with a code known only to Mikhail. Now, the main character must find the case and save his own life and that of his brother.