‘You’d better tell us,’ Nancy said, more softly. ‘Tell us everything.’

‘Miss Marchmont has a daughter. She lives south of the river, off Brixton Hill. Nobody’s meant to know because—’

‘Because what, Billy?’

‘She’s black, Nance. Hélène and Sidney, he used to be in the orchestra, the devil with a trumpet. The one who died. Hélène had his daughter and she lives down there, with Sidney’s parents. It’s me who delivers them messages back and forth. And . . .’ Billy steeled himself, and Raymond had the distinct impression that here came the most terrible secret of all. ‘Once Vivienne knew, she made me make another promise. She wants to dance tonight, you see. She wants to be on the dance floor, behind her mask, for everyone to swoon and gawp over, for everyone to think she’s the star . . . And then she wants to rip off her mask and reveal herself – all so’s her mother and Lord Edgerton get the shock of their lives. So she wrote a letter. She made me deliver it. She made me deliver it to Miss Marchmont . . .’

Raymond looked over his shoulder. From the other side of the dressing room, Nathaniel was still staring at them, his hands placed squarely on his hips.

Raymond looked back at Billy. ‘I think,’ he said, ‘you’d better tell us exactly what that letter said – before it’s too late.’

*

The omnibus was already driving off by the time Hélène reached out for its doors. By some strange mercy, the driver noticed her and slowed the engine. ‘Climb aboard, love. There you go. Don’t want you stuck out on a night like this, do we?’

Hélène was still quaking as she found a seat. Pressed up against the window, she opened up the telegram and scoured its words again.

*

Hélène, come at once. Sybil woke last night with a fever. You must come at once. It has a hold on her, Hélène. Come at once. She needs her mama. There may not be another chance.

*

The paper strained where she held it. Sybil was so near, and yet a lifetime away. What did the ballroom matter, what did any of it matter? A winter like this could kill the strongest of men. What hope for a little girl with an infection racking her chest? She looked up through the window at the endless white as Regent Street turned into the Circus at Piccadilly. The great billboards peered down, advertising all manner of wares, and it was all Hélène could do not to scream, and scream, and scream.

*

At the ballroom dressing-room doors, Raymond froze.

‘Billy, you bastard. Billy, you fool. Go after her. Go now. Well, you’re the only one who knows where she’s gone, aren’t you?’