The second half of the film is primarily concerned with the legend of the lost city of Kitezh.
Her friends — magic wood masters, working in NUINU (Scientific Universal Institute of Extraordinary Services, a NIICHAVO subsidiary in Kitezhgrad; for NIICHAVO see Monday Begins on Saturday) - decides to interfere and help to save the love.
The story is based on the legend of the Invisible City of Kitezh (made into a 4-act opera by Rimsky-Korsakov in 1907), which disappears under the waters of a lake to escape an attack by the Mongols.
Rimsky-Korsakov and Belsky first became interested in writing an opera on the Kitezh legend during the winter of 1898-1899, while they were working on the libretto to The Tale of Tsar Saltan.