'You might go off me. You might change your mind. You're a good-looking bloke. Some other woman might fall off a building and land on you and you might like it. You could get ill. You could get knocked off that motorbike.'

'ETA two minutes,' said Donna, gazing at the satnav. 'I'm not listening, honest.'

'You could say that about anyone. So what? So we sit there and do nothing every day in case we have an accident? Is that really how to live?' He swerved to the left so that I had to hang on to my seat.

'I'm still a doughnut, okay?' I said. 'I want to be a bun. I really do. But I'm still a doughnut.'

'Jesus, Lou! We're all doughnuts! You think I didn't watch my sister being eaten by cancer and know that my heart was going to break, not just for her but for her son, every day of my life? You think I don't know how that feels? There's only one response, and I can tell you this because I see it every day. You live. And you throw yourself into everything and try not to think about the bruises.'

'Oh, that's lovely,' said Donna, nodding.

'I'm trying, Sam. You have no idea how far I've come.'

And then we were there. The sign for Kingsbury estate loomed in front of us. We drove in through a huge archway, past a car park and into a darkened courtyard, where Sam pulled up and swore softly.

'Dammit. We were meant to drop you off.'

'I didn't like to interrupt,' said Donna.

'I'll wait here till you get back.' I crossed my arms.'There's no point.' Sam jumped out of the driver's door and grabbed his pack. 'I'm not going to jump through hoops to convince you to be with me. Oh, c.r.a.p. The b.l.o.o.d.y signs are missing. He could be anywhere.'

I gazed out at the forbidding maroon-brick buildings. There were probably twenty stairwells in those blocks and none you would have wanted to walk around without the company of a large bodyguard.

Donna shrugged her way into her jacket. 'The last time I came here heart attack it took four tries to find the right block, and that gate was locked. We had to find a caretaker to unlock it before we could bring in the mobile unit. By the time I made it to the right flat the patient was dead.'

'Two gang shootings here last month.'

'You want me to call in a police escort?' said Donna.

'No. No time.'

It was eerily quiet, even though it was barely eight p.m. These were estates in a part of the city where only a few years ago children might have been playing out on bikes, sneaking cigarettes and catcalling long into the evening. Now residents double-locked their doors long before dark, and windows were braced with decorative metal bars. Half the sodium lights had been shot out, and the odd remaining one flickered intermittently, as if uncertain whether it was safe to shine.

Sam and Donna, now outside the cab, were talking, their voices lowered. Donna opened the pa.s.senger door, reached in and handed me a high-visibility jacket. 'Right. Put that on and come with us. He doesn't feel safe leaving you here.'

'Why couldn't he '

'Oh, you two! For G.o.d's sake! Look, I'm going to head this way, you follow him that way. Okay?'

I stared at her.

'Sort it out afterwards.' She strode off, her walkie-talkie buzzing in her hand.

I followed close behind Sam as we went along one length of concrete walkway, then another.

'Savernake House,' he muttered. 'How the h.e.l.l are we supposed to know which one is Savernake?'

The radio hissed. 'Control, can we have some guidance? No signs on these buildings, and no idea where this patient is.'

'Sorry,' the voice said apologetically. 'Our map doesn't show individual block names.'

'Want me to head off that way?' I said, pointing in front of us. 'Then we'll have three walkways covered. I've got my phone with me.' We halted in a stairwell that reeked of urine and the stale fat of old takeaway cartons. The walkways sat in shadow, only the occasional m.u.f.fled burble of a television behind the windows suggesting life deep within each small flat. I had expected a distant commotion, some vibration in the air that would lead us to the injured. But this was eerily still.

'No. Stay close, okay?'

I saw that having me there was making him nervous. I wondered whether I should just leave, but I didn't want to find my way out by myself.

Sam stopped at the end of the walkway. He turned, shaking his head, his mouth compressed. Donna's voice crackled across the radio: 'Nothing this end.' And then we heard a shout.

'There,' I said, following the sound. On the other side of the square, in the half-light, we saw a crouching figure, a body on the ground under the sodium lights.

'Here we go,' said Sam, and we started to run.Speed was everything in his job, he had once told me. It was one of the first things paramedics were taught the difference a few seconds could make to someone's chances of survival. If the patient was bleeding out, had had a stroke or a heart attack, it could be those critical few seconds that kept them alive.

We bolted along the concrete walkways, down the reeking, dingy stairs, and then we were across the worn gra.s.s towards the prostrate figure.

Donna was already down beside her.

'A girl.' Sam dropped his pack. 'I'm sure they said it was a man.'

As Donna checked her for injuries, he called into Control.

'Yup. Young male, late teens, Afro-Caribbean appearance,' the dispatcher responded.

Sam clicked off his radio. 'They must have misheard. It's like b.l.o.o.d.y Chinese whispers some days.'

She was about sixteen, her hair neatly braided, her limbs sprawled as if she had recently fallen. She was strangely peaceful. I wondered, fleetingly, if that was how I had looked when he'd found me.

'Can you hear me, sweetheart?'

She didn't move. He checked her pupils, her pulse, her airways. She was breathing, and there was no obvious sign of injury. Yet she seemed completely non-responsive. He checked all around her a second time, staring at his equipment.

'Is she alive?'

Sam's eyes met Donna's. He straightened up and glanced around him, thinking. He gazed up at the windows of the estate. They stared down at us like blank, unfriendly eyes. Then he motioned us over and spoke quietly. 'Something's not right. Look, I'm going to do the drop-hand test. And when I do, I want you to head for the rig and start the engine. If it's what I think it is we need to get out of here.'

'Drugs ambush?' muttered Donna, her gaze sliding behind me.

'Might be. Or turf-related. We should have had a Location Match. I'm sure this is where Andy Gibson had that shooting.'

I tried to keep my voice calm. 'What's the drop-hand test?'

'I'm going to lift her hand and drop it from above her face. If she's acting, she'll move her hand rather than hit her own face. They always do. It's like a reflex. But if there's someone watching, I don't want them to get wind that we've worked it out. Louisa, you act like you're going to get some more equipment, okay? I'll do it once you've texted me to say you're at the rig. If anyone's near it, don't go in. Just turn round and come straight back to me. Donna, get your pack together, and ready. You go after her. If they see two of us leaving together they'll know.'

He handed me the keys. I picked up a bag, as if it were mine, and started to walk briskly towards the ambulance. I was suddenly conscious of unseen people watching from the shadows; my heartbeat was thumping in my ears. I tried to make my face expressionless, my movements purposeful.

The walk along the echoing concourse felt achingly long. When I reached the ambulance, I let out a sigh of relief. I reached for the keys, opened the door, and as I stepped up, a voice called from the shadows, 'Miss.' I glanced behind me. Nothing. 'Miss.'

A young boy appeared from behind a concrete pillar, another behind him, a hoodie pulled forward to obscure his face. I took a step back towards the rig, my heart racing. 'I've got back-up on the way,' I said, trying to keep my voice steady. 'There's no drugs in here. You both need to back off. Okay?''Miss. He's by the bins. They don't want you to get to him. He's bleeding real bad, miss. That's why Emeka's cousin is faking it out there. To distract youse. So youse'll go away.'

'What? What do you mean?'

'He's by the bins. You got to help him, miss.'

'What? Where are the bins?'

But the boy glanced warily behind him, and when I turned to ask again, they had disappeared into the shadows.

I glanced around, trying to work out where he meant. And then I spied it, over by the garages the protruding edge of a bright green plastic rubbish container. I edged along the shadows of the ground-floor walkway, out of view of the main square, until I saw an open doorway out to the refuse area. I ran over, and there, tucked behind the recycling bin, a pair of legs sprawled, tracksuit bottoms soaked with blood.

His upper half was slumped under the containers and I crouched down. The boy turned his head and groaned quietly.

'h.e.l.lo? Can you hear me?'

'They got me.'

Blood seeped stickily from what looked like two wounds to his legs. 'They got me ...'

I grabbed my phone and called Sam, my voice low and urgent. 'I'm over by the bins, to your right.

Please. Come quick.'

I could see him, looking around slowly until he spotted me. Two elderly people, Samaritans from a previous age, had appeared beside him. I could see them asking questions about the fallen girl, their faces blanketed with concern. He gently placed a blanket over the faking cousin, asking them to watch over her, then walked briskly towards the rig with his bag, as if to get more equipment. Donna had vanished.

I opened the bag he'd given me, ripping open a pack of gauze and placing it over the boy's leg, but there was so much blood. 'Okay. Someone's coming to help. We'll have you in the ambulance in a moment.' I sounded like someone out of a bad film. I had no idea what else to say. Come on, Sam.

'You gotta get me out of here.' The boy groaned. I put my hand on his arm, trying to keep calm. Come on, Sam. Where the h.e.l.l are you? And suddenly I heard the rig's engine starting, and there it was, reversing through the garages towards me at some speed, its engine whining in protest. It b.u.mped to a halt, and Donna jumped out. She ran towards me, threw open the back doors. 'Help me put him in,' she said.

'We're getting out of here.'

There was no time for gurneys. Somewhere above I heard shouting, multiple footsteps. We shouldered the boy towards the ambulance, shoving him into the back. Donna slammed the doors behind him and I ran for the cab, my heart racing, and threw myself in, locking the doors. I could see them now, a gang of men, racing towards us around the upper floor, hands raised with what? Guns? Knives? I felt something grow liquid inside me. I looked out of the window. Sam was walking along the open s.p.a.ce, his face turned to the sky: he had seen them too.

Donna saw before he did: the gun, raised in the man's hand. She swore loudly and slammed the rig into reverse, steering it round the garage, headed straight for the gra.s.sed area where Sam was still walking towards us. I could just make him out, the green of his uniform growing larger in the pa.s.senger mirror.

'Sam!' I yelled out of my window.He glanced at me, then up at them. 'Leave the ambulance alone,' he yelled at the men, over the whine of the ambulance's reverse gear. 'Back off, all right? We're just doing our jobs.'

'Not now, Sam. Not now,' Donna said, under her breath.

The men kept running, peering over as if calculating the quickest way down, relentless, moving forward like a tide. One vaulted nimbly over a wall, swinging his way easily down a flight of stairs. I wanted to skid out of there so badly I was limp with it.

But Sam was still walking towards them, his hands raised, palms up. 'Leave the ambulance, boys, okay? We're just here to help.' His voice was calm and authoritative, betraying none of the fear that I felt.

And then I saw through the back window that the men had slowed. They were walking now, not running. A distant part of me thought, Oh, thank G.o.d. The boy lay behind us, still moaning.

'That's it,' said Donna, leaning around. 'Come on, Sam. In you come. Come on over here now. And we can get the '

Bang.

The sound cut through the air, amplified in the empty s.p.a.ce so that I felt, briefly, as if my whole head had expanded and contracted with the sound. And then, too quickly Bang.

I yelped.

'What the f-' Donna yelled.

'We need to get out of here, man!' the boy shouted.

I looked back, willing Sam to get in. Get in now. Please. But Sam had gone. No, not gone. There was something on the ground: a high-visibility jacket. A yellow stain on the grey concrete.

Everything stopped.

No, I thought. No.

The ambulance screeched to a halt. Then Donna was out, and I was running after her. Sam was motionless and there was blood, so much blood, seeping outwards in a steadily expanding pool around him. In the distance the two old people scrambled stiffly towards the safety of their door, the girl who was supposedly immobile sprinting across the gra.s.s at the speed of an athlete. And the men were still coming, running down the upper walkway towards us. I tasted metal in my mouth.

'Lou! Grab him.' We hauled Sam towards the back of the rig. He was leaden, as if he were deliberately resisting. I pulled at his collar, his armpits, my breath coming in short bursts. His face was chalk-white, huge black shadows under his half-closed eyes, as if he had not slept for a hundred years.

His blood against my skin. Why had I not known how warm blood is? Donna was already in the rig, hauling at him, and we were pushing, heaving, a sob in my throat as I pulled at his arms, his legs. 'Help me!' I was shouting, as if there was anyone who could. 'Help me!'

And then he was in, his leg at the wrong angle, and the doors slammed behind me.

Crack! Something hit the top of the rig. I screamed and ducked. Some part of me thought absently, Is this it? Is this how I die, in my bad jeans, while a few miles away my parents argue about birthday cakes with my sister? The boy on the gurney was screaming, his voice shrill with fear. And then the ambulance skidded forwards, steering right as the men approached us from the left. I saw a hand rise, and thought I heard a gunshot. I ducked again instinctively.

'b.l.o.o.d.y h.e.l.l!' Donna swore and swerved again.I raised my head. I could make out the exit. Donna steered hard left, then right, the ambulance almost on two wheels as she hurled it around the corner. The wing mirror clipped a car. Someone dived towards us but Donna swerved once more and kept going. I heard the thump of an angry fist on the side. And then we were out on the road, and the young men were behind us, slowing to a furious, defeated jog as they watched us go.

'Jesus.'

The blue light on, Donna radioing ahead to the hospital, words I couldn't make out through the thumping in my ears. I was cradling Sam's face, grey and covered with a fine sheen, his eyes gla.s.sy. He was completely silent.

'What do I do?' I yelled at Donna. 'What do I do?' She screeched around a roundabout and her head swivelled briefly towards me. 'Find the injury. What can you see?'

'It's his stomach. There's a hole. Two holes. There is so much blood. Oh, G.o.d, there's so much blood.'

My hands came away red and glossy. My breath came in short bursts. I felt, briefly, as if I might faint.

'I need you to be calm now, Louisa, okay? Is he breathing? Can you feel a pulse?'

I checked, felt something inside me sag with relief. 'Yes.'

'I can't stop. We're too close. Elevate his feet, okay? Push up his knees. Keep the blood near his chest.

Now make sure his shirt is open. Rip it. Just get to it. Can you describe the wound?'

That stomach, which had lain warm and smooth and solid against mine, now a red, gaping mess. A sob escaped my throat. 'Oh, G.o.d ...'

'Don't you panic now, Louisa. You hear me? We're nearly there. You have to apply pressure. Come on, you can do this. Use the gauze from the pack. The big one. Whatever, just stop him bleeding out. Okay?'

She turned back to the road, sending the ambulance the wrong way up a one-way street. The boy on the gurney swore softly, now lost in his own private world of pain. Ahead, cars swerved obediently out of the way on the sodium-lit road, waves parting on the tarmac. A siren, always a siren. 'Paramedic down. I repeat paramedic down. Gunshot wound to the abdomen!' Donna yelled into the radio. 'ETA three minutes. We're going to need a crash cart.'

I unwrapped the bandages, my hands shaking, and ripped open Sam's shirt, bracing myself as the ambulance tore round corners. How could this be the man who had been arguing with me just fifteen minutes earlier? How could someone so solid just be ebbing away in front of me?