The Case of the Sleepwalker's Niece is a crime novel in the Perry Mason detective series. It features a millionaire with the bad habit of sleepwalking  with a bloody carving knife in his hand; his beautiful, astrology buff niece; a hypochondriac, black-sheep-of-the-family half-brother; a golddigging ex-wife and a crackpot inventor who may be a crook. When a man is murdered at in the millionaire's Hollywood mansion, the sleepwalker is the chief suspect and it is up to Perry Mason to find out the truth. Erle Stanley Gardner (1889 – 1970) was an American lawyer and author, best known for the Perry Mason series of detective stories. Perry Mason features in 82 novels and 4 short stories, the character was inspired by famed Los Angeles criminal defense attorney Earl Rogers. Published by Penguin Books in 1959. Book is in good condition. Binding intact.