Strahan: The Desert Moon Mystery

Three murders and a suicide plague the Desert Moon Ranch—one of them a lovely girl with a secret. No clues, yet clues everywhere. Days and nights of suspense, danger, suspicion. Rancher Sam Stanley, his housekeeper Mary Magin, and the rest of the household were getting along fine until the arrival of the twin girls, Danielle and Gabrielle. After the murders begin, the household is unnerved and accusations fly. But, it is not until the arrival of Miss Lynn MacDonald, private detective, that the strange and deadly puzzle is solved. 

The Desert Moon Mystery was published in 1928.