Neither of us say a word as we pile into the car and I start the engine. The silence continues past the Broadwalk shopping centre and down the Wells Road. Only when I stop the car at the traffic lights by the Three Lamps junction and Kira pulls her iPod out of her jacket pocket do I speak.

‘What was that all about?’

‘Sorry?’ She looks at me in alarm, as though she’s forgotten I’m sitting next to her.

‘You and Jake, earlier.’

‘It was just …’ She stares at the red stop light as though willing it to change to green. Without her thick black eyeliner and generous dusting of bronzing powder her heart-shaped face looks pale and the sprinkle of freckles across her nose makes her look younger than she is. ‘Just … a thing … just an argument.’

‘It looked serious.’

‘It got a bit out of hand, that’s all.’

‘I’m guessing Jake didn’t go to bed last night.’

‘No. He didn’t.’

‘Oh God.’ I sigh heavily. ‘Now I’m even more worried about him.’

‘Are you?’

I feel a pang of pain at the surprise in her eyes. ‘Of course. He’s my son.’

‘He’s not Billy, though, is he?’

‘What’s that supposed to mean?’

‘Nothing. Sorry. I don’t know why I said that.’

I wait for her to say more but no words come. Instead she reaches into her handbag, pulls out a black eyeliner and flips down the sun visor. Her lips part as she draws a thick black ring around each eye, then dabs concealer on the raised, discoloured patch of skin near her right temple. It looks like the beginning of a bruise.

The red light turns amber, then green and I press on the accelerator.

Neither of us speaks for several minutes. I glance across at Kira, at the lump on her temple, and my stomach lurches.

‘Did Jake hit you?’

‘What?’

‘When you were fighting over the bottle. There’s a bruise on your head. Did he hit you?’

‘God, no!’

‘So how did you get the bruise?’

‘At the club last night.’ She flips down the visor and examines the side of her head in the mirror, prodding it appraisingly with her index finger. ‘I dropped my mobile and hit my head on the corner of the table when I bent down to get it.’

‘Kira, I know I’m not your mum but you’re the nearest thing I’ve got to a daughter and if I thought anyone was hurting you—’

She slaps the visor shut. ‘Jake didn’t hit me. All right? He’d never do something like that. I can’t believe you’d say something like that about your own son.’

I tighten my grip on the steering wheel.

‘Sorry,’ she says quickly. ‘I know you’re trying to look out for me but—’