Preface

The day it started was one of the most normal days ever- a warm, summery morning in June with not a cloud in the sky and the birds singing as usual. The sun streaming down, baking the pavements of London and coaxing people from their homes in their thousands. Some may say it was perfect.

Sherlock Holmes knew better.

He had sensed a shift in the air, a change in the atmosphere around him, weeks ago now, leading him to believe that something was not quite right. It was strange, but everything seemed a little too perfect for this sprawling urban city, this industry-affected dwelling perching on the skin of the United Kingdom, clinging to the fabric of this Earth. Sherlock knew that something had changed, noticed that this summer there was something different lingering in London.

He just didn't expect it to lead to this.

Chapter One- Fever

"Molly! Molly Hooper!"

The paramedics were frantic. There were at least fifteen of them, twenty at most, all huddled around one table, all wearing the same wide-eyed, terrified gaze. A few stood behind, the nervous students too scared to do anything about what was lying on that table. Or, rather, what was fighting against the desperate restraints of the weary paramedics as they held it down with their bare hands, trembling and trying to dodge the gnashing teeth of the thing.

"Molly!" the same voice bellowed.

Molly Hooper burst through the double doors of the mortuary, brown hair falling from its ponytail and face pale with worry. Her eyes widened when she saw what was going on.

"Another one?" she cried, making for the medicine cupboard where the anaesthetic was kept. Preparing the needle as quickly as she could, she tried to control her shaking, usually careful fingers as she pushed through the gaggle of people to reach the creature on the table. Spying a clear section of skin, pale grey and rubbery, she sank the needle into the body, trying to block out the screams of the thing as it shuddered and came to a standstill, muscles tensing and joints locking.

There was silence in the room, and everyone fell back from the body, breathing hard and trying to calm their racing heartbeats. Molly instantaneously wheeled the table into a spare room, discarding the body underneath a white body bag, knowing that it wouldn't stay inanimate for long. Shoving the door shut and locking it tightly, the young pathologist double-checked the locks before turning to face the shaken paramedics. She noticed black blood spattered on their blue hospital scrubs and her stomach turned over.

"Was anyone bitten? Anyone in this room?"

No one spoke, but there were accusing glances shot at everyone there. Anybody doubted everybody; Molly saw their heated glares and they reminded her a little of the eyes of wild dogs, feral and merciless. She could sense that an argument may break out, so she stomped over to where they were standing, staring at each and every one until they focused their attentions back on her.

"How did it happen?" she demanded, asking the oldest paramedic there. His nametag said Peter and he looked about forty, with salt-and-pepper hair and tired blue eyes.

"We don't know," he replied gruffly, "when we got to him, he'd already been pronounced dead at the scene. It was a heart attack that killed him."

"Killed him?" Molly felt a little weak in the knees, "what do you mean, killed him? He was alive- still is!"

"It's a different case to the others we've seen- it's unlike anything we've ever seen before. It's worse. The fever came after death, Miss Hooper, not before. Before, the fever killed them, but it's… it's working the other way round."

Molly sank down into a chair, heart pounding. This had never happened before- all day they'd been receiving calls of a strange fever which burned the victim out completely, killing them stone dead within minutes. Before death, the victim was known to go into a frenzied, almost cannibalistic state of violent disorientation. They didn't know what had caused it, but had learned that the virus could be passed on through the blood; which meant if you were bitten, you were done for. You would be dead in under a quarter of an hour.

This… this was something new. Something very, very dangerous. Molly tried not to panic as she thought of the consequences if there were any more cases of this happening. It could spread throughout the UK- even worse, Europe. What if this went worldwide? Molly dipped her hand into her pocket, numb fingers closing around her mobile. She slipped off the chair and made for the door, grabbing her coat and bag without bothering to exchange her lab coat for her normal one.

"Where are you going?" called out Peter, voice shaking a little. Molly looked back at them all, these shaking, tremulous humans crouching in the shadows of the morgue, scared and feeble. She did not want to be one of them. She wanted to put a stop to this before it got even worse.

"To get help."

Molly took a cab from outside St Bart's Hospital, gabbling directions to the taxi driver as she held her phone to her ear, praying it wouldn't go to voicemail. It didn't, thank God, and Molly was grateful to hear a familiar voice on the other end of the line.

"Sherlock Holmes."

"Sherlock! Sherlock, it's Molly- there's something going on, and I need your help." Molly's words were rushed and fraught with worry.

"What do you mean? Molly, are you alright?"

"I'm fine, I'm fine, but something really weird is going on and I don't know what else to do!"

"It's okay, I'll be at the hospital straight away-"

"No!" Molly's shout made the cabby's head turn. She dismissed him rather rudely with a wave of her hand- but manners were hardly important now.

"I'm already on my way to 221B- please, I'll explain when I get to you, but just stay where you are."

Ten minutes later and Molly scrambled out of the taxi, shoving a twenty quid note into the driver's hand. She was on Baker Street and getting strange sideways looks from the customers in Speedy's Café as she jogged on the spot, trembling. She looked a little like an escaped mental patient.

"Keep the change," she told him, grabbing her bag and coat before he drove away into the dense London traffic. The door to 221B opened and there was Sherlock, brow furrowed but not a hair out of place, not a rumple in his black suit as he studied Molly with those hypnotic quicksilver eyes.

"Molly, are you alright? What's happened? You're bleeding, Molly-"

"It's not mine," she said breathlessly as Sherlock moved out of her way. She needed to explain as soon as possible. The pathologist rubbed at the black bloodstain on the sleeve of her lab coat as she took the stairs two at a time, Sherlock frowning at her back in puzzlement as he followed. As she pushed open the door to the living room of 221B, the detective opened his mouth to speak, at the same time John Watson stood from his chair, newspaper in his hands.

"Molly?" John started, but was shushed by Sherlock, who looked very concerned indeed. His eyes were dark with worry. Molly looked like she'd been dragged through a hedge backwards as she stood uncomfortably by the window of the men's flat, her hair in a loose, scruffy ponytail. Restlessly she tugged the hair elastic out, letting her brown locks tumble down her tremulous shoulders. Her eyes flickered back and forth, as if expecting something to attack her at any moment. Sherlock touched her arm awkwardly.

"Can I get you anything?" he muttered, eyes trained on the frenetic Molly. She shook her head robotically.

"No, thank you." She was too wired to eat or drink anything. Turning to the two men, she gulped before speaking.

"All day, something strange has been going on," she started, "something that no one at the hospital has ever seen before. It's… it's abnormal. It's as if… well… it's as if the dead are coming back to life."

John stared at the pathologist as if she'd just eaten a puppy.

"Molly," he said carefully, "are you alright? Have you got a fever?"

"I'm not crazy, if that's what you're implying," she snapped at the army doctor. With eyes like fire and a blazing stare, she glared at John until he retreated. He not Sherlock had ever seen her like this before.

"Sorry," she muttered, dropping her gaze to the floor, "I know how it must sound. But it's true, there's something happening beyond our control! The mortuary's full of bodies that should be long dead and they're banging at the door of the storeroom like prisoners! I'm not crazy!"

"She's right."

Molly and John turned their heads to stare at Sherlock, who was leaning against the desk, long legs crossed in front of him and ice blue eyes solemn. He was looking at the smiley-face he'd spray painted on the patterned wallpaper ages ago, face calm and relaxed.

"What?" they asked simultaneously, as the detective walked over to the kitchen, cool as ever. Silently he scooped up a test tube with a cork tightly shoved in the top that contained a sort of black liquid inside. The bubbling substance caught Molly's eye and she hurried over to look at it, taking the fragile tube from Sherlock's hands when he offered it to her.

"This is…" a shudder ran down Molly's spine.

"Blood. Yes. Human."

"Or what was human," she muttered to herself, glancing down at her sleeve. Sherlock did the same, narrowing his eyes at the stain.

"Let me see?" he asked- Molly lifted her arm for him to examine closer. He even sniffed it, which made him wrinkle his aquiline nose in disgust. Sherlock let her arm go, biting his lip. For once, he looked unsure.

"Did you get bitten?" he asked Molly urgently, his eyes alight with something she couldn't place. Worry? Fear? She shook her head.

"I got that from when I put the body to sleep," she explained, "some of it splashed onto my arm when I put the needle in."

Sherlock nodded curtly, turning away and leaving Molly holding the repulsive test tube. John came to stand beside her, looking at the test tube with about as much interest as a teenager in a maths class.

"You should be more interested in this, you know," Molly muttered to him, "you wouldn't want to end up like those poor creatures tied up in the mortuary."

John Watson stared at the bubbling black fluid inside the test tube, shuddering a little. He definitely didn't, whatever the 'creatures' were. And, glancing at Molly's lab coat, that blood would be a nightmare to lift.