A young seamstress wearing a velvet mask is strangled in Paris's La Villette district, a black unicorn medallion left beside her body. Within days two wealthy, respected men are found brutally murdered. Victor Legris cannot resist this tantalizing puzzle, and soon he is embroiled in the shady dealings of a fashionable dressmaking workshop and a clandestine society of the rich and powerful. But he risks exposing secrets buried for decades, ones many people are desperate to keep hidden...