College professor Hank Hinkley and his assistant, Elrod Elmo, embark on a peaceful vacation on the picturesque island of Martha's Vineyard in Massachusetts. Convening at the lovely Up-Island Inn, they settle in for a relaxing, upscale getaway. While the inn is chock-full of colorful personalities, one guest in particular catches Hinkley's attention: a man tied to a twenty-year-old, unsolved Boston bank robbery. Apparently, someone else also takes an interest in this mysterious guest because he's soon mortally wounded in a nearby cemetery. As he dies, he whispers a cryptic message. Are his last words a clue to the identity of his murderer? Or is he simply referencing the Boston bank robbery? Hinkley and Elmo are determined to find the murderer, but they'll soon discover that the other guests aren't visiting the Up-Island Inn for its lovely view or gourmet breakfast. Three million dollars is still missing from the bank robbery, and most of the guests appear to be amateur treasure hunters. Soon the inn's patrons begin dropping like flies as the race to uncover the murderer and the money becomes dangerous. It's up to Hinkley and Elmo to solve the mystery before anyone else ends up unconscious, missing, or dead.