Here, the headstones speak of wealth and respectability. They are clean and sturdy, and the engravings are more ornate. Most are white or pale grey in colour, but Simon comes to a halt before a marker made of black marble.

Constance Edith Carfax

18th October 1810–23rd September 1840

Respice Finem

Dark spots cloud her vision. This is worse than seeing Constance’s shade appear at the séance. All her sister’s complexity has been reduced to a collection of stern, unforgiving words.

When Constance died, Agnes vowed never to give her another thought, yet she has always been there, concealed, like an organ that cannot be removed. She remembers Miss West’s description of sisterhood, and it is true: she feels love and hate, blended together. It is impossible to distinguish where one ends and the other begins.

Constance was controlling, and vicious, and grasping, yes. But her sole desire in life was to be with Agnes, always. In the grand scheme of things, in comparison with the abuse Pearl faced, that does not seem so very bad. For all her violent outbursts, Constance never once injured Agnes. Would never have poisoned her with matchsticks. In her own way, she loved her.

Maybe Agnes should have spoken to the shadow when it arose. If she had offered forgiveness then, it might have finally put Constance to rest.

‘I should have thought,’ she starts, but her voice croaks out. She swallows, tries again. ‘I should have … brought more pansies.’

Somewhere, a bird calls.

Simon’s eyes seem to peel beneath her skin. ‘Look, Miss Darken,’ he says, and it is a voice she has never heard him use before. ‘Look closely. See … beside her.’

There are three slabs of black marble, she realises. They stand out like the sharps and flats on a piano, but they are in a line, clumped together.

Cedric Matthew Carfax

Agatha Darken

Shock holds her immobile.

Simon grips her arm. All she can think is that this is some kind of joke, a monstrous joke, but the names are carved … indelible.

‘No. No, it cannot be.’ Simon does not speak. ‘You promised me. You told me that you knew where Cedric …’

Her legs give way.

Simon kneels with her. She feels his arm encircle her shoulders; inhales the aroma of carbolic soap.

‘Who could … I don’t … Was it Miss West? Did she kill them? How? When?’

‘The dates.’ Simon crafts his words with care. ‘Please, Miss Darken. Observe the dates.’

Her eyes skate wildly over the shining black marble.

‘I cannot …’

Simon waves a bottle of salts beneath her nose and then everything comes into terrible focus.

The date of death for all three is the same:

23rd September 1840

‘They have been dead these fourteen years,’ he breathes.

Memories crackle at the corners of her mind. Although the ground is firm beneath her knees, she feels herself being dragged down.