"When Cara and Brendan first meet, she's fresh out of college with a degree in the fine arts, recovering from the recent death of her mother and spending time on Martha's Vineyard while trying to figure out her next steps. She's swept away by Brendan's humor and charm and intoxicated by his thrilling, dangerous secret. He claims -- no, he insists -- that he he can breathe underwater. He shows Cara his gills. He dives beneath the waves and doesn't...