Ruby is bent over another tray – brooches this time – when she hears the door open behind her. The assistant looks up and smiles at a new customer, a gentleman in a dark overcoat. The man is looking for a gift for his wife. He sounds uncertain, like a man unused to fripperies but trying his best. An anniversary, she hears him say. Twenty years.

She strokes the brooch she is about to swap and asks if she may look at it in the mirror, hold it to her coat. The assistant nods, comfortable with her presence in the store and keen to help the gentleman in his deliberation. A man who does not know what he is looking for, after all, is a man who might be persuaded to spend more money than he intends.

Ruby picks the brooch from the tray and carries it carefully to a small oval mirror at the end of the counter. It is extremely fine – better even than the crescent moon she swiped from Enderby’s. Two concentric circles of platinum set with diamonds and a translucent emerald in the centre. It is nearly two inches in diameter. She imagines wearing this one on the satin gown of her dreams; how it will gleam at her shoulder when she enters the room. She sees a grand staircase, film stars gathered, and all eyes on her as she sweeps, slowly, languidly, down white marble steps.

In the mirror, she can see that the gentleman in the dark overcoat is watching her. She half-recognises him but cannot quite place his face. Someone she has danced with at the Angel, perhaps.

She puts down the mirror and smiles at the assistant. ‘It’s lovely,’ she says. ‘I think I’ll ask my father for this one.’

She replaces Solly’s brooch in the tray.

The gentleman in the coat frowns at it. He appears puzzled.

Something about him makes her anxious. Something in his face, the way his head turns, the way he looks at her.

Inspector MacKenzie.

She is unable to stop the gasp of recognition, but quickly turns it into a cough, as she lurches for the door.

‘Bolt the door, man!’ MacKenzie shouts. ‘It’s Ruby Mills.’

But he is too slow. The doorman has opened the door to admit new customers and Ruby slips between them like an eel.

She hears MacKenzie shouting, furious, apologising to the couple he has crashed into, yelling to the doorman to catch her.

‘Maggs!’

She has enough breath to call to her friend as she passes at speed, her hand clutching her skirt and lifting it to her knees.