Allergic to all kinds of group activities, Serenata Terpsichore, the protagonist of this novel, is a voice-over artist who has dedicated her life to exercising, running, swimming, and bicycling. Now, when she turns sixty, so much of her activity takes a painful toll on her in the form of osteoarthritis. For her part, Remington Alabaster, her always sedentary husband, has just been forcibly retired from the Albany Department of Transportation after a confusing confrontation with his new boss, and decides to choose precisely that moment to discover the benefits of gymnastics and run a marathon. After joining the fitness fever that is increasingly present in the modern world, the once moderate Remington becomes an insufferable narcissist, and hires a strict (and seductive) personal trainer, with whom he will train with for competitions. As furious as she is concerned, Serenata will discover that the tenacity of an early retiree with a lot of free time who insists on defying age should not be underestimated.