Agnes adds more water, makes the ink thinner and thinner as it reaches the back of Mrs Campbell’s head. The woman appears to be falling through an empty, white space. She picks up a needle, ready to scrape in some finer detail.

‘Are you nearly finished?’ Mrs Campbell complains.

Maybe Constance has actually appeared to help defend her against this fussy customer. It amuses her to think of how icily her sister would have treated a woman like Mrs Campbell. Mamma once said: ‘If Constance loves anyone, it is you, Agnes.’ But she is not sure if that was true. She only remembers feeling tied to her little sister. As if she were a doll Constance wanted to carry about with her everywhere: something to own and control.

On the day Montague left, Constance took her hand and said, ‘Now he will never part us.’ As if that were some kind of comfort.

Well, death has parted them. And although her ghost might be trying, Constance cannot really get back to her now.

Agnes is no spirit medium. She cannot be possessed.

‘Is it ready?’ Mrs Campbell persists.

‘Almost.’ Agnes lays the needle down and signs her work. It is charming, despite its subject. The painted woman is silent and without Mrs Campbell’s haughty expression; she has even managed to capture the wispy lace in her hair. ‘Here. Please be gentle with it. Some parts may still be wet.’

Mrs Campbell comes over to the table and beams down at her shadow self. ‘Well! That is more like it. What do you think, Lavinia? Is not Mamma very handsome?’

Lavinia just blinks.

‘A treasure,’ Mrs Campbell continues, scooping it up. ‘Wait until my friends see! An actual silhouette from the infamous Darken’s Parlour. I will be the envy of Laura Place.’

Agnes grimaces. ‘Allow me to show you out.’

When they gain the hallway, Mrs Campbell produces her purse. ‘Make yourself useful, Lavinia, hold the shade.’

Her smooth, pale hands tell out the coins, four and six as promised, without the slightest demur about Lavinia’s failed portrait. How rich she must be, to fritter money away like that.

Agnes closes her fist tight over the treasure.

‘You should take a cab home,’ she advises. ‘The streets are filthy.’

Opening the front door illustrates her point. Greyish-brown mush heaps the pavements. What was beautiful and snowy has melted into formlessness once more. It smells, too, possibly the effect of thaw water running down the drains.

‘Nothing like a walk for the constitution,’ Mrs Campbell announces, striding out without a backwards glance.

Lavinia raises her eyes to heaven and mopes after her, still carrying the shade.

Agnes watches them nervously from the threshold. She ought to shut the cold out, but how can she? She must see her customers safe, at least until they have turned the corner. She has a dreadful feeling that she has just signed their death warrant.