Cal Hodges, chief investigator for a Chicago law firm, and his attorney wife, Merle, must find a stolen diamond-encrusted 15th century stickpin, which has already caused one murder and may cause several more unless the thief is captured. On anything but a vacation, Cal and Merle know the murderer is one of their fellow passengers on a river cruise to Prague, but which one? They also know the priceless stickpin is hidden on board, but where? Also endangered is the romance between Cal's assistant, Edwards, and Merle's sister, Taylor. The elusive and seduction Elisha also returns to tempt Cal.