The first germs of this story came to me during the 2016 Jane Austen Festival in Bath. My friends and I attended a wonderful talk and workshop with silhouette artist Charles Burns, who was kind enough to let us loose on his own physiognotrace – with hilarious results! Charles Burns’s instructive book, Mastering Silhouettes (Fil Rouge Press Ltd, 2012) also proved a key resource for me in writing about Agnes’s work. I cannot thank him enough!

Pearl’s experiences with spiritualism were largely inspired by the memoirs of Victorian-era spirit medium Elizabeth d’Espérance, quoted at the beginning of this book, but those conversant with the topic will recognise that the name of her ‘spirit guide’ Florence King is a nod to the famous medium Katie King, who supposedly ‘materialised’ the spirit of Florence Cook in the 1870s. Missives from Summerland is a fictional newspaper, very loosely based on the Medium and Daybreak. Similarly, the Bath Society of Spiritual Adventurers is my own invention: I did not wish to associate my fraudulent characters with real people of genuine spiritual belief.

I am indebted to Harriet Martineau’s Letters on Mesmerism and Wendy Moore’s biography The Mesmerist for helping me to create Myrtle’s world. The Queen of Crime herself, Agatha Christie, must also be thanked for her novel Dumb Witness, which sparked the idea for phosphorus at a séance.

Pearl’s physical appearance was inspired by Miss Millie Lamar, ‘The White Fairy’, who worked as a mind reader in 1890s America. In the Victorian era, it was sadly common for the unscrupulous to monetarise albinism, as is evidenced by the employment of a number of people with albinism in P. T. Barnum’s travelling circus.

My version of Victorian Bath is based on the Cotterell map and Vivian’s ‘Street Directory’ from 1852, plus local information discovered in the British Newspaper Archive. The characters’ houses are of course fictional. Any mistakes are my own. The weather of 1854, I purposefully changed for my own devices.

I have borrowed some names from my mother’s family for this tale; she had both an Auntie Aggie and a paternal cousin whose surname was Darken. I hope they will not mind me using them in this way – I must stress that the names are the only similarities!

On a personal note I would like to thank my husband, Kevin, to whom the book is dedicated. He came up with the title long before we had heard of the del Toro film! My agent, Juliet Mushens, who somehow still talks to me after reading my early drafts, and the wonderful team at Raven Books. My special thanks always go to Alison Hennessey, Lilidh Kendrick, Philippa Noar, Amy Donegan, Sara Helen Binney and David Mann, but I am sure there are many other silent heroes working behind the scenes who I never meet. My heartfelt gratitude to you all.