The Case of Jennie Brice by Mary Roberts Rinehart

The flood brings in not only the muddy waters but a series of suspicious clues that convinced Mrs. Pitman, a boarding house keeper, that a murder has been committed at her boarding house. Jennifer Ladley aka Jennie Brice is missing and with the help of Mr. Holcombe, a quirky gentleman with a passion for mysteries, they embark on a quest for the truth behind the disappearance of Jennie Brice.