During the summer of 1983, Elaine and her daughters, Hannah and Daisy, move into 'Sunset Terrace', a squalid, low-rent apartment building in Los Angeles that houses single mothers. They have been on the road for three years, driving from town to town in a flight from tragedy ever since Hannah discovered her father dead in his study. While Elaine struggles to make ends meet and construct a new life for herself in California, Hannah - a shy, lonely girl whose only companion in the shuffle of schools has been her pet turtle - develops an earnest affection for Bridget, a vivacious, foul-mouthed nine-year-old in Apartment One who was abandoned as an infant in a supermarket parking lot. Bridget quickly becomes Hannah's best friend, teaching her how to play tricks and climb a chain-link fence and steal candy. Elaine becomes captivated by Bridget as well, encouraging her to come over for dinners and sleepovers, taking on the role of a surrogate mother. Compelled by pity for the wayward girl, Elaine is blind to Bridget's dangerous influence on Hannah, who at the summer's end takes part in a malicious game that irrevocably alters the course of all of their lives.