Mary is out of options. Estranged from her Evangelist family, plagued by debt collectors and beset by chronic pain, Mary signs up for a mysterious job advertised as 'The Girlfriend Experiment' (or, The GX). Masterminded by a successful Hollywood actor with a string of failed relationships behind him, The GX seeks to pin down and capture the essence of love before it fades, and to answer the question of why two people, drawn together by forces beyond their control, can wake up one day as strangers to one another. Mary is hired to play the part of 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. From a writer whose debut was hailed as one of the literary events of 2014 comes a novel of die-hard faith and fleeting love; of questions which probe the depths of our society, and answers that will leave you reeling.