When Annie Darling, the popular proprietress of the Death on Demand bookstore, throws a cruise party with guests dressing up as their favorite fictional sleuths, it's a success—that is until one of the revelers plunges overboard and faux murder turns into real-life death. As the body count begins to rise, Annie begins to suspect foul play. Enlisting the help of her investigator-spouse, Max, best friend and customer Henny Brawley, local bestselling superstar Emma Lloyd and Annie's mother-in-law, Laurel, Annie searches for answers, convinced that the victims were all connected in some way. But time is running out, since the killer they seek is far more intelligent and efficient than most.