The Sign of Five (2nd in the Holmes and Holmes Series)

After young private-eye Sheridan (Sherry) Holmes explains how Sherlock Holmes came to live in her San Francisco apartment, her grandmother, Tessa - a writing teacher and author of romance novels - brings a student with a problem, Carmen Abbott, to see Sherry. The young woman has been sent a lot of money by her father, who had disappeared thirty years before. Her father now deceased, Carmen - along with Sherry, Tessa and Mark Watson - learn that Abbott and his four buddies had made a lot of money by card-counting at blackjack in Las Vegas casinos. Trapped by a lie, they spent years in jail but are now out and expecting to uncover the money they’d hidden - and split it up. But, of course, one of the five has decided to try to keep all the money for himself, leading to a desperate hunt for the thief, the help of a tar-sniffing dog, and a middle-of-the-night speed-boat chase across San Francisco bay.