Sister Ursula, a Los Angeles nun who makes a habit of sleuthing, tackles a locked room murder in this "delightful . . . original" mystery classic (The New York Times Book Review).   Anthony Boucher was a literary renaissance man: an Edgar Award-winning mystery reviewer, an esteemed editor of the Hugo Award-winning Magazine of Fantasy and Science Fiction, a prolific scriptwriter of radio mystery programs, and an accomplished writer of mystery, science fiction, fantasy, and horror. With a particular fondness for the locked room mystery, Boucher created such iconic sleuths as Los Angeles PI Fergus O'Breen, amateur sleuth Sister Ursula, and alcoholic ex-cop Nick Noble.   The guilty better say their prayers when Sister Ursula is on the case--in this acclaimed mystery novel, which remains "as expert as a fencer's skill and as fresh as a daisy" (The New York Times Book Review).   The head of the Children of Light, cloaked in his yellow robe, has placed the ancient curse of the Nine Times Nine upon Wolfe Harrigan, the famed author and debunker of cults, who naturally scoffs. The next day, Wolfe's assistant, Matt Duncan, sees something in the window of Wolfe's study that throws him into a panic: a man in a yellow robe.   When Wolfe is found alone and dead inside the study, the police are stumped. All the windows were locked, and Wolfe's sister, who was sitting right outside the door, claims she saw no one come out. The baffling case doesn't add up for family friend Sister Ursula. But she'll need a miracle if she hopes to divine the truth before the killer strikes again . . .