Sara glanced at her sister to see if she had noticed, but she was staring ahead with a fixed expression that indicated she knew exactly what was going on, but was choosing to ignore it.

The ballet school was a jaunty sort of a place. The walls were painted in vivid hues of purple and hot pink. Framed black and white photographs of Rudolf Nureyev and Margot Fonteyn lined the corridor that led from the entrance to the rabbit warren of changing rooms at the back of the building. It was the sort of place where appearance mattered, but the glossy smiles and not-a-hair-out-of-place buns hid a diseased heart.

The Carter sisters had pleaded to give up ballet but their mother wouldn’t let them. It was good for their posture, apparently. For discipline.

Sara placed her ballet case on the bench that lipped the far wall. Her older sister opened a locker and hung up her coat. As Shannon bent to untie her trainers, a hairbrush bounced off her back.

The older girl straightened up, anger tugging at her features, narrowing her eyes and thinning her lips. ‘Who threw that?’ Her eyes, hard as slate, swept in a slow half-circle around the room, but all the girls were looking away, busying themselves by taking off their outdoor clothes or tying up the silken ribbons of their shoes. Someone giggled.

‘Are you OK?’ Sara pressed closer to her sister. ‘Did it hurt?’

Shannon dismissed her sister’s concern with a head shake and a couple of strands of white-blonde hair worked themselves free. She bit her lip. For a second time, she bent over to untie her laces, her gaze flicking warily upwards every now and again.

From across the changing room, a foil package of sandwiches hit the side of her face. Followed by a cereal bar. A banana. Two packets of crisps.

‘Stop it!’ Sara shouted. Even though Shannon had warned her to stay out of it. Even though Shannon had side-stepped the small pile of food and was calmly pulling off her jeans. ‘Just stop it.’

‘Ickle sister’s fighting your battles now,’ said a tall girl with acne. She smirked as she adjusted her leotard to stop it from cutting into her inner thigh. ‘Can’t you speak for yourself?’

‘Yeah, Shannon,’ said another girl. ‘Are you’ – she adopted a baby voice – ‘scared?’

Shannon slammed the locker door. It made a loud, metallic clang that demanded attention. Her shoulders rose as she drew in a breath. She swung around to face them.

‘Shut your mouth, Orla Brookes.’

Sara put a hand on her arm to calm her, but Shannon shook it off, eyes like stones.

‘She speaks,’ said Acne Girl, looking around at the other girls, inviting them to be complicit in her baiting. ‘The creature actually speaks.’

Acne Girl – Sara didn’t know her name, but recognized her as a pupil from Shannon’s school – whispered something to Orla, a wiry, muscular girl.