From the day Sissy fights a boy in the playground in front of Tegan, they realise they are not like the other girls. Both raised in unusual families, they become so close they feel like one being, wrapped around each other in bed at sleepovers, sending photographs to men they meet online, scaring each other with reports of the girls being snatched at night in their town. But as their rituals push against the boundaries not only of childhood, but of possibility, Sissy feels herself transforming into something strange and terrifying.

Sissy is used to being on the outside. The new girl in her West Country school, she recently arrived with her troubled mother, prone to letting Sissy fend for herself.

But from the day Sissy fights a boy in front of Tegan, she's no longer alone. Bonded by violence, they grow so close they feel like one being: wrapped around each other in bed at sleepovers, sending photographs to men they meet online, and scaring each other with reports of the girls being snatched at night in their town.

Over the course of the school year, they find themselves on the threshold of girlhood, with threats gathering thick and fast around them. And as their make-believe worlds bleed into their daily lives, Sissy feels herself transforming into something strange and terrifying.

Amphibian is a tender, haunting coming-of-age debut about desire, precocity and the intensity of early friendships that have the power to upend our lives.