1898August 1898. The men of St. Petersburg are divided into two camps of ardent fans: they are driven crazy by the “most beautiful woman in the world” Lina Cavalieri and the “queen of diamonds” Carolina Otero, performing at the private Aquarium theater. Which one is the best singer: Italian or Spanish? This should be decided by the “fight of butterflies” that the capital is expecting. Suddenly, danger looms over the stars: the corpse of an unknown woman is found in the theater, and the voice of a ghost is heard at night. Will detective police official Rodion Vanzarov be strong enough to save them? Or will Aquarium become a death trap? The underbelly of the theatrical world, unsightly, cruel and full of intrigue. How to unravel a tangle of secrets if human lives and the life of Vanzarov himself are at stake?