Mona (Nathalie Press) conceals her intellect and her want for more out of her daily life; and the well-educated Tamsin (Emily Blunt) is her absolute opposite. Tamsin’s personality shows her as being both spoiled and cynical. Shared fascination and attraction bonds the two young women over the course of a summer. Mona's elder brother Phil (Paddy Considine) has turned to religious zeal to cleanse him of his criminal past. Phil tries to impress his new beliefs on his sister. The struggle between love and faith within Mona’s own bliss with Tamsin is central. The women’s love for one another is tested and questioned.