‘Suit yourself,’ Stephanie called after her. ‘I’ll be here when you change your mind.’

Wandering out of the art block in a daze, Lottie was disorientated to find it was already dark. The paths were lit up by soft orange floor lights, but in this part of the school there was something creepy about them, like an anglerfish was leading her into its jaws.

Her head was still sore over her failure to get any information about Ellie’s tattoo. She was lost, no closer to solving Claude’s strange letters or figuring out how to help Ellie.

‘Excuse me, Princess.’

Lottie turned to find a Year One girl staring up at her, a vacant expression spinning in her eyes, not quite focused, and all Lottie’s nurturing instincts kicked in.

‘What’s wrong? Are you OK?’

The girl continued to stare up at her, her blank face like a fish out of water, and strangest of all was her dried lips and out-of-place hair, almost as if she had lost all sense of her body.

‘Are you hurt?’

Without warning, the girl’s hand shot out as fast as a frog’s tongue, her fingers wrapping tightly round Lottie’s wrist, and with a jerk she pulled Lottie behind the art building.

Lottie tried to prise herself free, clawing at the girl’s fingers, but she kept pulling, dragging Lottie with surprising strength past the walls and windows of classrooms and through the school grounds, far away from other students. That’s when Lottie smelled it, the sickly-sweet smell making her nose crinkle in disgust. It was a scent she loathed to recognize – the Hamelin Formula.

With one last tug, the girl pulled Lottie into a narrow gap between the old and new art block where only a sliver of light could reach them, and where two eyes glinted out at her from behind brown glasses.

Haru grabbed Lottie’s shoulder, righting her before she fell to the ground from the girl’s aggressive thrust. She was so shocked she could hardly move, slowly coming to terms with how stupid she’d been. She’d got cocky, been lulled into a false sense of security, forgetting that Haru was still a threat, that he was always there, watching them, and at any moment he could use that formula on one of the students like the poor Year One girl who continued to sway on the spot.

‘Stay right there,’ he called over Lottie to the poisoned girl behind them and Lottie glared up at him. ‘Don’t worry.’ He shrugged, letting go of her at last. ‘It’ll leave her system completely in about a week.’

Shaking off her confusion over why Haru had ended his hour with Jamie early, she became angry at what he’d done to this girl. ‘You promised you wouldn’t hurt anyone else.’ Lottie had never considered herself the type to growl, but right now she was dangerously close to it.