Cassie [Hannah Murray] is the central character of Pure. Cassie has returned from the USA, alone. As she negotiates a somewhat solitary new life in London, she finds friendship in unexpected places. Her identity is shaped by her friendship with young photographer Jacob. But as she gets noticed, she finds it harder and harder to deal with being a public person. Set against this, is a story of her relationship with her father, newly widowed, who is making a hash of bringing up her little brother. Finally, Cassie finds a way of staying pure to herself but at a high cost.