Chapter One
 
 Darkness pooled around the underground platform as Michelle stepped out of the carriage.With a hiss, the doors closed behind her, and the train shrieked as it disappeared into the wide mouth of the tunnel to continue its journey.She snuggled deeper into her coat, shouldered her bag, and followed in the footsteps of the single other passenger who had gotten off at this Tube station.
 
 It had been a busy day—but then again, in the crowded wards of the hospital, every day was a busy day.She was glad of the silence of the night after the chaotic and loud shift she had just had.It was impressive, really, the sheer racket that a four-year-old who did not want to receive an IV could produce.The high-pitched screeches still rang in her ears.
 
 She followed the winding way of the underground station until she was disgorged onto the dark streets of the London suburb she lived in.Only a short walk and she would be at her apartment.She couldn’t wait to take off her shoes, put on her pyjamas and watch an episode of her favourite TV show,Harrogate Homicides, the long-running crime drama she had been a fan of for years.It was the season finale—the murderer would be revealed and justice would be restored in the sleepy English village.A perfect ending to an exhausting Thursday.
 
 She walked past the handful of takeaways that lined the main road, their bright fluorescent lights illuminating the pavement.It wasn’t completely quiet, of course.London was never truly still, its millions of inhabitants coming and going, chatting, laughing, drinking, fighting.Just a couple more streets until she was home.The glow of the brightly lit shops faded behind her.
 
 A loud thud stopped her in her tracks.A wheeze followed, which made her think of a punctured lung.She stood only a couple of paces from the mouth to a dark alleyway, a place where the light of the street lamps could not quite reach.Another thump, this one sounding like flesh pounding into flesh.Michelle’s heart started to slam against her ribcage.Her hand slid into her pocket, enclosing her phone.It wouldn’t be the first time that someone was fighting in this neighbourhood.She would have a quick glance and call the police.Interfering was a fool’s errand, but at the same time, she couldn’t just walk away.What if someone was being robbed?What if someone was in real trouble?She couldn’t just leave someone hurt, helpless.She crept closer, her comfortable sneakers quiet on the asphalt.
 
 Another thud, and a low voice swearing.It sounded like a woman’s voice.Bracing herself, Michelle peeked around the corner, staying as close to the brick wall as she could, fervently hoping that the shadows would hide her in case anyone was looking in her direction.
 
 It took a moment for her to realise what she was seeing.In the darkness, two shapes writhed.There was something about them, something about the way they moved, that looked wrong.But before she had time to consider this more closely, the shapes detached, the metallic glint of a blade flashed between them.A shriek rent the air; a dark liquid drenched the ground.
 
 Michelle swore under her breath.This didn’t look like a drunken brawl.She had no idea what this was, but it was bad.Really, really bad.She pulled her phone from her pocket.She had to call the police, call an ambulance.Probably both.
 
 Before she could dial, a crash sounded, and she started.Her phone slipped from her fingers and tumbled onto the ground with a sharp crack.For a moment she was torn between picking up her phone, its screen surely shattered, and running for help.She could go into one of the shops, ask them to call the emergency number.
 
 A low moan came from the alleyway.What the hell was going on?Heart beating in her throat, she hazarded another glance around the corner.The scene had changed substantially.There was only one person now—a woman slumped against the wall, clutching her side.The scant light that made its way into the alley glimmered on a black wetness that covered her hands.Behind her, a dark shape flitted around the corner, disappearing into the night.
 
 “Shit,” Michelle said, all caution thrown to the wind.She ran to the woman, medical training kicking in.She assessed her quickly in a single glance, noting her pale skin (possible result of blood loss), the sweat on her brow (possible shock), the dilating pupils (could be drugs, could be something else).There were no wounds visible except for the one on her side.
 
 “Let me have a look,” Michelle said, peeling the woman’s hands away from her abdomen without waiting for a response.The woman’s white T-shirt was soaked with what could only be blood.
 
 “Wait—” the woman said, but Michelle lifted the T-shirt, the fabric reluctantly releasing from the wet skin.The woman’s abdomen was surprisingly muscular.She quickly assessed the depth and size of the wound and lowered it again.
 
 “You need medical attention,” Michelle said.“It doesn’t look like it hit anything vital, but you need to go to the hospital to be sure.”
 
 The woman laughed: a deep, throaty laugh.More details swam into focus now that Michelle had a moment to take a breath.The woman was tall—slightly taller than Michelle, but not by much.She seemed about thirty, a bit younger maybe.She was very beautiful.Her skin was smooth, her features perfectly symmetrical with high cheekbones and a full mouth.She wore her long blonde hair in a low ponytail.The chill of the clear autumn night didn’t seem to bother her—she wore only a T-shirt and jeans.If she had taken some kind of drug, she might not even notice the cold.Michelle frowned and shrugged off her coat.
 
 “You probably need stitches,” she continued.“You may want to sit down or you could pass out from the blood loss.”
 
 The woman was still smiling.Michelle didn’t understand what was so funny, but then again, people did weird things when they were in shock (or high).“I’ll be fine,” the woman said.
 
 “Sure,” Michelle answered.She balled up her coat and pressed it onto the wound.“Here, hold this, I’m going to grab my phone real quick and call an ambulance for you.”The woman placed her right hand over the coat, but before Michelle could take a single step back to the opening of the alleyway, the woman’s left hand gripped her arm like a vice.
 
 “That won’t be necessary,” the woman said.
 
 “Look, I get that you might feel fine now, but once the adrenaline wears off…” Michelle remonstrated.Truly, half the battle with patients was convincing them that they needed help.Then again, most of her patients usually didn’t reach up much past her hip.
 
 “I’ll be fine,” she repeated.The woman lifted the coat and revealed the wound on her abdomen.“See?”
 
 Michelle glanced at the wound again, expecting to see the same gash framed with blood on the woman’s stomach.She squinted in the dim lighting of the alleyway.Did it…?It looked better.She leaned closer, not quite believing her eyes.She’d been so certain that the slash had torn through several layers of skin and into the muscle underneath.It had looked pretty nasty, oozing with blood.Now much of that blood had gone and some of the flesh had knitted together.But that was impossible.Immediately, Michelle started to doubt her earlier assessment.Perhaps the lack of light and her anxiety had made her think the wound was more dangerous than it actually was.But that was nothing like her.Even when patients were in critical condition, she usually kept her head.
 
 She glanced back at the coat that the woman still clutched.The amount of blood on her shirt was incongruous with this small scratch.Something wasn’t adding up.Before she could investigate further, the woman pulled at Michelle’s arm and kindly but insistently led her back towards the main street.Michelle’s phone lay face-down where it had fallen.In a daze, Michelle picked it up.A spiderweb of cracks covered the screen.
 
 “As you can see, I’m perfectly fine.There is no need to worry.”The woman’s voice was soothing, like she was speaking to a spooked animal.“It was very kind of you to look after me, but you can go home now.I will walk with you, just to see you home safe.Looks like there are plenty of pickpockets around here.”
 
 Pickpockets?Michelle’s mind was reeling.Was that what she saw earlier, a thief?Her memories were fragmented now, moments only surviving as flashes, and none of the images that rose to her mind added up to a mugging.What was that strange shape she had seen fleeing the scene?Where was the blade that she had noticed?She tried to glance back into the alley, seeking out the gleam of a knife, but the woman whisked her onwards.The woman kept up a steady stream of chatter in her low, calm voice.She is trying to distract me, Michelle thought.But distract me from what?
 
 “Such a shame about your phone.It looks like the screen hit the ground the wrong way.I hope you can have it repaired.What way were you going?Down this street?Great.It’s a nice night, isn’t it?The moon is so clear in the sky…” After several more inane remarks on the weather, Michelle’s apartment building came into view.It was a rather nondescript five-storey structure made of crumbling concrete.It wasn’t pretty, but it was home.
 
 “This is where I live,” Michelle said.Fear was building in the pit of her stomach now that the adrenaline was fading.Something wasn’t right here.She had gotten herself caught in something bad.What was it?Was this woman a drug dealer?Had she stepped into some kind of drug war?You heard about those things on the news all the time, of people getting killed for being in the wrong place at the wrong time, didn’t you?But if it was a drug thing, then why had the other shape seemed so…inhuman?
 
 The woman finally let go of Michelle’s arm, and she suddenly found herself missing the support, feeling unmoored in the night.She stared at the woman mutely, unsure of what to say.
 
 “Oh, your coat.”The woman held out the bloodied jean jacket.“Sorry about—”