Eliza Keenan is the mother of two young sons, the owner of a flower studio that caters to the city's elite, and the loving wife of a deliciously rumpled math professor named Andrew. She's on the move from dawn until her boys are in bed, and after they're asleep she cleans her house. Her one complaint about her life is that the only time she has for herself is her twice-weekly swim in the local community centre pool, where sunlight shines in through a tall window and lights up the water in a way that reminds her of the year she spent as a footloose youth on an island in Greece. Then one morning into this life that is full of satisfactions of all kinds except sexual (because who has the time or the energy once the kids are asleep?) comes a tall, dark and lovely stranger, a young woman Eliza encounters at the pool and nicknames 'the Amazon.' The sight of this woman, naked in the change room, completely undoes Eliza, and soon the two of them are entangled in an affair that breaks all the rules, and threatens to capsize not only Eliza and her happy family, but her lover's world, too. And yet the sex is so all-encompassing, so intimate, so true ... how can it be bad?