This day will change him forever, though he doesn’t know it yet.

Detective Inspector Zachariah Boateng laces up his trainers on the stairs. Pats his pockets: wallet, keys. All set.

‘Let’s go, Dad, come on!’ Amelia bounces on tiptoes. ‘Can I have it now?’

Zac raises his eyebrows.

‘Please,’ she adds, her smile revealing the little gap between her front teeth. She extends a palm.

Fishing in his wallet, he produces two pounds fifty. Sixteen years in the Met Police and he’s a pushover for a nine-year-old.

‘Back soon, love,’ he calls down the hallway. His wife, Etta, raises a mug of tea in acknowledgement, phone clamped to the side of her face. Miles Davis’s trumpet drifts in from the living room. Through the kitchen window he can make out Kofi, their five-year-old, punting a football in the garden.

Pulling the front door to, he squints in the sunlight. The air is already warm, heat coming off the pavement. Amelia skips ahead, singing to herself.

‘Not too far, Ammy.’

Watching her, he remembers the tiny bundle Etta handed to him in the hospital. That first day, he held her as if she were made of glass. A time will come when she doesn’t want to be seen with him, when the highlight of her Saturday is no longer their ritual of pocket money and sweets. Enjoy this while it lasts, he tells himself.

The morning is still, quiet. Ahead, Amelia turns off the road, confident on their well-trodden route to the newsagent at the top of Peckham Rye Park.

‘Stay where I can see you’

Turning the corner, he glimpses a flash of her yellow dress disappearing around the next bend. Relax, he thinks. She knows where she’s going, it’s only one street away. Maybe he’ll pick up a weekend paper. Do they need milk, or—

Sound rips the air.

Crack. Crack. Crack.

Zac freezes. No mistake: a handgun, 9 mm. He starts running.

Crack, crack.

‘Amelia!’ He can’t see her up ahead.

Crack.

Zac’s body tells him to get away. Police training and a Father’s instinct propel him towards the noise.

Crack.

Louder now.

‘Amelia! Where are you?’

A motorbike engine revs hard. Shouting, screaming.

He reaches the main road and turns, scanning, frantic. No sign of her.

‘Amelia!’

The newsagent. Two people are outside, staring.

‘I’m a police officer.’ He pushes through, smashes the door open with his shoulder.

The young man at the counter is motionless. Face down on the floor, three small entry wounds in his back, blood pooling around him.

A gasp from the next aisle.

‘Please God, no,’ he whispers.

There she is, on her back, feet splayed. Eyes shut, breathing quickly, a red stain expanding rapidly in the centre of her yellow dress.

‘Get an ambulance,’ he yells through the open door. ‘Call a fucking ambulance!’

Kneeling next to her, he presses one hand on the wound and feels warm liquid oozing over his skin. His throat constricts.

‘Shh’ He cups her head in his other hand. ‘It’s going to be ok, Ammy.’

Her eyes open a fraction. ‘Daddy.’

The blood isn’t stopping.

‘I’m here.’ He pushes down harder and she moans. ‘Help’s coming, baby.’

‘I’ve called 999.’ A woman from outside stands in the doorway.

‘Check his pulse.’ Zac nods at the young man’s body. What the hell happened here?

‘Daddy, I’m tired.’

Losing consciousness, getting colder. He clamps both hands to the wound now. ‘Come on, Ammy, stay awake.’

Her eyes shut and flicker open. ‘I want to sleep.’

‘No!’ he barks. ‘You’ve got to keep your eyes open, do you understand?’ Zac hears the desperation in his voice. Her only chance is to stay conscious. Keep her talking.

‘What happened, Ammy? What did you see?’

Her breath is slowing now. ‘Man.’

‘A man?’

She drifts again, eyes closing. When they open, her gaze is unfocused.

‘Ammy! Look at me.’

Tilting her head, for a second she’s with him. Then lost again. She draws a long breath.

His hands are soaked, slippery. Leaning over, he turns a cheek to her mouth and looks down her chest. Waits. Counts to ten. No air, no movement.

Puts two fingers on her carotid artery.

No pulse.

Scrambling to his feet, he lunges past the shop counter, searching for the box. Please, God, let them have a defib here. Please.

Behind the counter the older Bangladeshi owner is slumped on the floor, his blood splattered over the cigarette boxes stacked in the open cabinet above him.

‘Jesus Christ.’

And no defib box.

‘He’s dead.’ The woman stands and steps back from the young man, her trouser legs dark where she’s knelt in the puddle of blood.

‘Check him too.’ Zac nods down to the shop owner.

Racing back to Amelia, he kneels again and begins compressions. Both hands, fingers interlaced, his body weight bearing down on her. Pumps hard, counting aloud. On twelve some ribs crack. He keeps going. Twenty-nine thirty.

Zac pinches her nose and tilts her chin down. Covers her mouth with his own and breathes into her slowly. Her chest rises and he watches it fall. A second breath. His hands are trembling as he returns to compressions. Thirty more. Harder. Two breaths.

She doesn’t move.

‘He’s dead as well,’ the woman calls.

‘Help me!’ shouts Zac. ‘Press on the wound here. Seal it off. Ammy, come on.’

The woman kneels next to him and pushes on Amelia’s abdomen. ‘You know her?’

‘She’s my…’ His voice cracks. ‘My daughter.’ Tears are falling onto her body. He keeps pumping his hands over her chest. But she feels cold now. Thirty more. Two breaths. Wipes his eyes on his sleeves. Keeps going.

Nothing.

‘Please,’ he mumbles, gathering her in, clutching her tight to him. ‘Ammy, don’t…’

Facial muscles straining, tears flowing, he barely makes a sound.

The siren comes too late.