The first spark was joined by another, ricocheting up Olympe’s arms. Like a flame catching, the charge consumed her in a rush, sending her hair flying wildly about her head and catching the light of the stars in her eyes.

The battalion shrank as one, Camille scrambling to escape the storm. She could just make out the tear-stained bruises around Olympe’s eyes. She called her name, but the girl didn’t respond. The hum was crackling louder and faster, rushing over her like a river raging from its banks. Sparks caught on scraps, chairs, their bundles of supplies, filling the room with curls of smoke. A wind whipped from Olympe’s floating figure, scattering Ada’s books, flinging Camille’s hair over her eyes. She could feel the charge in her teeth, in her bones, an awful, insistent hum that filled the inside of her head until she could barely stand it. Somewhere in the mayhem, Ada had crawled over to Olympe and reached for her hand, but a flare shot painfully between them and she let go.

‘I won’t do it!’ wailed Olympe. She hung in the centre of the room, feet dangling a few centimetres off the floor, wrapped in shimmering blue. ‘I can’t – I won’t hurt more people, I won’t … I won’t…’

Camille called to Olympe but it was no good. Ada was crawling towards her again – past her, down to the crypt. Camille hesitated. Maybe Ada was right: they should all get out of there. But then Ada reappeared clutching an old silk dress, ruined beyond repair, from a previous job. Holding it in front of her, she took tentative steps towards Olympe.

Camille understood what she meant to do a moment before she did it, yelling Ada’s name. Then Ada was lunging forwards, wrapping the silk around Olympe, pulling her into a tight hug, like a mother wrapping a towel around her child fresh from the bath. Camille held her breath, sparks escaping from around the edges of the silk, but Ada had Olympe’s arms pinned, smothering the worst of the charge.

‘We won’t let anyone use you,’ she said, holding Olympe close. Her curly hair was clouding out from the charge in the air. ‘Olympe – let us help you.’

Slowly, the frenzied blue crackling dimmed. The charge died, and the wind died with it. The ringing in Camille’s head receded. She took a shaky breath, as she watched Ada bring Olympe back to the ground. Finally, Ada sat with her on the floor and used the gown to mop away the tears on her cheeks.

‘You have a choice. It’s why they made you, but it’s not who you are.’

Camille wanted to say more, but in that moment her mind was blank. It wasn’t Olympe’s fault, but they had done something awful. Innocent blood was on their hands. They weren’t helping people – they’d killed them.