Cape Cod's resident detective Asey Mayo has a long history with millionaire Bill Porter, owner of Potter Motors.

Bill's men's club, the Hybrid, has a long history of funny bets on the night of the big football game, but when Bill Porter's enemy Harper Dixon bets Bill $50,000 that Asey Mayo couldn't "solve his Aunt Eugenia's grocery order", Asey must take a hand on behalf of his old friend, and returns from Jamaica to a New England blizzard.

After they arrive, the group is locked in a powder room by a mysterious figure with a bright-red manicure.

Upon their release, they discover Aunt Charlotte Dixon, drowned in her washbasin while in the process of shampooing her hair.

When Asey Mayo learns that Aunt Eugenia's grocery order is the last thing she wrote before her death, he realizes that there is more at stake here than a bet.