In this slow-burn social thriller, The Amaranth is an isolated, luxury retirement village where the privileged and powerful live out their twilight years with amazing vitality. Here is where wealthy industrialist Richard Kendrick and his younger wife, Lily, move after he suffers a debilitating stroke. But while Richard is rejuvenated, thriving in the cultish atmosphere, Lily is disturbed by the transformations she observes in her spouse, then shocked by changes in her own physiology, prompting her to probe into the dark underbelly of this beautiful but menacing Shangri La.—Eileen Shields