A strange little case was planted on detective Andrei Pryazhnikov. A well-known banker was killed, and the main suspect, the modest “gray mouse” Alena, a bank cashier, disappeared without a trace. The investigation reaches a dead end, and the only clue is Alena's diary. The only pity is that the most interesting pages are missing from it. Already desperate to find a solution, Andrei meets a dazzlingly beautiful girl with the exotic name Dearly-Doo, who soon takes first place in his heart and thoughts. But the detective does not lose his vigilance! Doesn't your new girlfriend know too much about the banker's murder?..