Mary is out of options. Estranged from her family and beset by phantom pain, she signs up for 'The Girlfriend Experiment' - a mysterious project masterminded by a famous Hollywood actor who hires a collection of women to fulfil the different roles of a relationship. Mary is to play the Emotional Girlfriend, alongside a Maternal Girlfriend, a Mundane Girlfriend, an Angry Girlfriend and, of course, an Intimacy Team. Each woman has her debts and her difficulties, her past loves and her secrets. As Mary and the actor are drawn ever closer together, the nature of the experiment changes, and the Girlfriends find themselves exposed to new perils, foremost among them love.