“What could be more beautiful than sparkling scarlet rubies, cut into the shape of tulip petals and framed with dewdrop diamonds?” – this is probably what Lord Hamilton thought when ordering a gift for his beautiful wife. Neither the lord himself nor his wife could know that the wonderful stones would only bring them grief. And not only them. By the will of fate, having ended up in Russia after long wanderings, the marvelous rubies also harmed their new owners. According to legend, these stones feed... on human blood, changing their hue to a darker one every time the next owner faces imminent death... But St. Petersburg investigators have no time for beautiful and terrible legends - they must find and neutralize the killer of businessman Alexander Ryzhikov, and also find out who and why he killed sociology teacher Emma Hamilton...