The Perfume of the Lady in Black is a novel by Gaston Leroux, published in 1908. It is the second installment in the adventures of the journalist-detective Joseph Rouletabille.

In this sequel to The Mystery of the Yellow Room, reporter Joseph Rouletabille delves deeper into his personal investigation, tracing his past in America and the mysterious "lady in black," linked to his childhood. After solving the first case and securing Robert Darzac's release, the latter finally marries Mathilde Stangerson, but the danger persists with the escape of the criminal Ballmeyer.

Fearing a new attack, the characters take refuge in the Château des Rochers Rouges, where Rouletabille gradually uncovers disturbing connections between the protagonists: the lady in black, his mother, and Miss Stangerson are one and the same person, while his adversary Larsan is actually Ballmeyer, who is none other than his father.

As tension mounts, Ballmeyer manages to infiltrate the castle and attacks Robert Darzac, leaving him gravely wounded. Faced with this threat, Rouletabille must once again solve the mystery and put an end to the criminal's hold.