Annie Whitman's ordinary Midwest life is shattered with the sudden death of her husband Jack. Thirty-five and failing at life as a widow, she turns to the comforts of vodka in an attempt to camouflage the cold sheets of an empty bed. The necessary inebriation helps her to cope with Jack's death, but proves to be a deterrent in recovering any sense of normalcy. After spending several months at the bottom of a bottle, Annie stumbles upon a lockbox in the crawl space of her basement. Opening this box also opens her eyes to the likelihood that Jack Whitman might not have been the honest and doting man she married. Annie embarks on a mission to the Virgin Islands to uncover the truth about her husband's past and seek safety from her brother-in-law, who seems to be the captain of his own sinking ship. While settling into paradise, she meets the wickedly handsome, but surprisingly reserved Kessler Carlisle, who is struggling with his retirement from country music superstardom. With Kessler's help, Annie discovers the heart's uncanny ability to heal, and the possibility that dead men don't always keep their secrets-even if they're buried in the Caribbean waters of St. Croix. The Achilles Heel delves into the formidable fact that everyone harbors darkness, and some will go to the depths of the ocean to keep their secrets hidden.