Louise could never quite remember exactly what happened next. There was blood, and miniature lightning forks. Rachel Handley let out a clarion shriek. Shattered glass erupted from the frames of the oil paintings down half the length of the corridor as the blazing white lightning strobed violently.

Louise crammed her hands over her ears as the shriek threatened to crack open her skull. The lightning died away. When she looked up, instead of her father there was a hulking humanoid shape standing beside Rachel. It wore strange armour, made entirely of little squares of dark metal, embossed with scarlet runes, and tied together with brass wire. “Bitch!” it stormed at a quailing Mrs Charlsworth. Thick streamers of bright orange smoke were belching out of its eye slits.

Rachel Handley’s arms turned incandescent. She clamped her splayed fingers over Mrs Charlsworth’s cheeks, teeth bared in exertion as she pushed in. Skin sizzled and charred below her fingertips. Mrs Charlsworth mewed in agony. The maid released her. She slumped backwards, her head lolling to one side; and she looked at Louise, smiling as tears seeped down her ruined cheeks. “Go,” she mouthed.

The grievous plea seemed to kick directly into Louise’s nervous system. She pushed her shoulders into the wall, levering herself upright.

Mrs Charlsworth grinned mirthlessly as the maid and the burly warrior closed on her to consummate their vengeance. She raised the pathetic knitting needle again.

Ribbons of white fire snaked around Rachel’s arms as she grinned at her prey. Small balls of it dripped off her fingertips, flying horizontally towards the stricken woman, eating eagerly through the starched grey uniform. A booming laugh emerged from the clinking armour, mingling with Mrs Charlsworth’s gurgles of pain.