Jessica's latest book tour brings her to Tampa, Florida, where she meets up with an old friend, Cabot Cove's Dr. Seth Hazlitt. Seth is in town visiting Alvaro Vasquez, a renowned physician who is developing a potentially groundbreaking cure for Alzheimer's disease. If he's successful, his American backers stand to make millions. But there's a growing fear that the drug may fall into the wrong hands.

Jessica attends a party at Vasquez's lavish home, but the celebration ends abruptly when Vasquez seems to be struck by lightning. Jessica and Seth do some digging into the physician's checkered past and learn that his death was no accident. As they work together to find a cure for the common killer, they become enmeshed in international intrigue involving the local police, the FBI, and the CIA--and begin to wonder whether they'll ever see Cabot Cove again.