A qualified expert and restorer of international renown, Dmitry Starygin, was an adventurer by nature and, despite his quiet office job, experienced so many fascinating and dangerous adventures that they would have been enough for a dozen modest restorers. And this time, answering the request of a familiar pianist to inspect an antique harpsichord, Dmitry accidentally discovers that the instrument contains a hiding place where… sheet music of a popular old romance was kept. And what if the musical notation is a coded secret message?