At Christmas, touring artists are invited to Riga and give concerts in the Blackheads' house. Among the artists is the young Italian violin prodigy Niccolo Mancini - a strange, sickly boy who is mercilessly exploited by his own father. During the reception, a very expensive violin by the master Guarneri, which was given to the prodigy for the duration of the tour, but was not given as a gift, by a wealthy philanthropist, disappears. Ivan Andreevich Krylov is searching for the instrument. As always, he is helped by the princess's pupil Masha Sumarokova, the chemist David Hieronymus Grindel and the physicist Georg Friedrich Parrot. Naturally, the thief turns out to be the most unexpected character, and we manage to establish this with the help of... a pharmacist. But the violin does not return to the musician - it is sent to the owner by diplomatic mail. Read the long-awaited continuation of the brilliant novel “Cagliostro's Apprentice”!