The Catman of Paris plot
"BEWARE! A MONSTER IS LOOSE!"
After some exotic travels, the author Charles Regnier returns to Paris in 1896, having written a bestseller, which the Ministry of Justice had actually wanted to ban. That same night, a Justice Department official is killed in one of the dark alleyways...and scratched to death! The prefect of police suspects that Regnier is in some sort of "Dr. Jeckyll and Mr. Hyde's situation is settled, but Inspector Severen thinks there's nothing supernatural about Regnier's motive. Meanwhile, Regnier, who is now suffering from amnesia and has been nicknamed 'the Catman', is increasingly doubting himself, especially after he becomes delusional about a second murder.