Even some things are worth dying for, if just one man could stand tall. There would be some hope for us all.

THE DIOGENES CLUB BUNKER

"Have you lost your mind?" John all but spluttered.

Sherlock rolled his eyes. "And everyone accuses me of being a drama queen."

"Hey," Lestrade interjected. "He's just saying what we're all thinking Sherlock."

Glancing around the room at those gathered, Sherlock read the varying degrees of concern on all their faces. The one showing the most distress was Molly.

As his gaze came to rest upon his pathologist, Lestrade continued. "What you're suggesting doing is extremely dangerous. You can't do it on your own, you're gonna need help."

"No," Sherlock responded firmly.

"Sherlock…" Mary began. But Sherlock forestalled her with a raised hand and a shake of his head.

"I'm well aware that this task is extremely dangerous. But I also believe that its success rests in the ability to get as close to these Martian's without being detected. Therefore a single individual, and one who knows where best to direct the virus to achieve maximum affect, is the best and only solution."

Before the arguments could continue Sherlock picked up the bag he'd packed, containing the sample and a means of getting the virus into the Martians, and headed out of the room, pausing briefly to offer a reminder.

"Don't let your guard down around my brother until I get back." Or don't get back, was the unspoken subtext. "Hold on to hope for as long as you can. When you feel that there is no other alternative, then you can return this to him." Sherlock tossed the remote to John, who caught it easily.

THE DIOGENES CLUB – VISITOR'S ROOM

"Sherlock, wait!"

Sherlock paused as Molly rushed up to him.

"I'll go with you," she offered.

Sherlock looked down at the petite woman and allowed a small smile to play upon his lips. His loyal, dependable pathologist, what would he do without her? She was always there for him, whether it was helping him fake his own death, or in his Mind Palace to tell him what he needed to do after he'd been shot. She was willing to do anything to help him.

But not this time, this time he wouldn't allow it. He could not bare the thought of her being in harms way. She had to stay safe. If things didn't go well for him, then she was the only other person who knew what they'd done to the virus to manipulate it to make it more effective in its ability to infect the Martians at a more rapid rate.

It was absolutely imperative and essential that she stay behind.

As always with Molly, he didn't need to tell her any of this. She was the only one that truly saw him, and could read him better than most.

She tried to be brave as she nodded her head to show she understood, but she couldn't contain an audible sob escaping her lips, nor the tears as they spilled from her eyes to stream down her cheeks.

Seeing the tears broke something in the consulting detective, and before he could stop himself he lent down and gently pressed his lips to Molly's trembling ones, tasting the saltiness of her tears. Raising his head, he looked her directly in the eye. "I will do everything in my power to come back to you if I can. I promise." He quickly brushed his lips over her forehead, before turning to slip out of The Diogenes Club through a side door.

"You'd better," Molly whispered.

She stood motionless lost in thought, when she became aware of movement behind her. She turned to see Billy Wiggins hovering uncomfortably in the doorway, looking a little embarrassed at being caught observing what had clearly been a private moment.

But when he saw her worried expression, he made his way over to her, patting her awkwardly on the shoulder. "Don't worry missus, I'll keep an eye on 'im for ya," he promised.

Before Molly could respond he slipped out of the room and set off after the world's only consulting detective.

Silently Molly offered up a prayer that both would return from their dangerous mission safely.

LONDON - SEVERAL BLOCKS AWAY

Wiggins had managed to keep track of Sherlock from the time he'd left The Diogenes Club.

But the further they went into the city, the more unfamiliar London became. Wiggins was reminded of images he'd seen of the city during The Blitz.

Building were either completely destroyed, or in serious danger of toppling over. Several fires had broken out, and the unpleasant smell of rotting bodies filled the pungent air.

Covering almost every surface now was the red weed that continued to grow and spread at speed. But it too was struggling to survive. The normally fleshy red fibre was being replaced by a sickly white parasitic growth that covered the leathery fronds, strangling the flow of nurturance that guaranteed its survival. The alien weed became more and more decayed as the bacteria took hold.

Even the poisonous black smoke appeared to have less of an effect than before.

But this was of little concern to Billy, who kept his focus on the man he was following as stealthily as he could.

He was just following the Consulting Detective around a corner when he came to an abrupt halt. Sherlock had disappeared. Wiggins glanced left then right, but there was still no sign of the man he was pursuing.

"If you're determined to follow me undetected," noted a familiar voice from directly behind him. "You might want to try being a little less obvious about it."

Billy's shoulders slumped in defeat. He thought he'd been doing such a good job of tailing Sherlock.

"You need to go back, I don't require a chaperone." Sherlock stated dismissively.

But as he made to leave, Wiggins responded just as adamantly. "I'm not here for you."

Sherlock turned back to his self-appointed protégé. "So why are you here, Billy?" he asked contemptuously. Time was of the essence and this idle chitchat was quickly becoming tedious.

"I'm doing it for ya missus."

Sherlock frowned, clearly confused.

"The little one from the morgue," Billy clarified. "Promised her I'd keep an eye on ya."

Realising no argument would deter Wiggins from his task. Sherlock carried on in the direction he'd been going.

"UUUlllaaaHHHH!"

Both men halted in their tracks.

A moment later the cry came again. "UUUlllaaaHHHH!"

"Doesn't sound well," Billy noted.

"No it doesn't," Sherlock replied, his pace quickening.

Shortly after they came upon the body of the Martian that had been calling out. Its tripod stood completely motionless. The Martian had either left its machine of its own accord or fallen from it. Either way, it had ended up a crumpled mess on the ground. Its body showed clear signs of bacterial infection.

It confirmed to Sherlock that his and Molly's theory was correct. Bending down Sherlock collected a sample from the dead Martian. Analysis of the decaying flesh could give them more valuable data on how they could improve upon the virus they'd already created.

The virus that still needed to be put to the test.

They didn't have long to wait.

The ground beneath their feet began to shake. Glancing up they saw another tripod heading in their direction. It had clearly heard the cries from its fallen comrade and had come to investigate.

Sherlock quickly removed a remote controlled drone from his bag, inserted the phial containing the sample of the virus, and set the drone lose.

As the drone approached the compartment where the Martian sat, the alien invader completely ignored it, clearly viewing it to be too small to be of any significant threat.

And that would prove to be a fatal mistake, as Sherlock directed the drone to drop its load, the glass phial smashing on impact, releasing the virus.

Bacteria can get into anything, and this it did, working its way through the alien metal casing and attaching itself to the sole occupant.

Within minutes the tripod began to stagger about uncontrollably, before crashing to the ground, completely immobile. The Martian inside lay dead, slain by the Earth's minute, microscopic allies.

But the virus' job was not yet complete. What hadn't entered the tripod had been picked up by a gentle breeze. And everything alien it touched, the red weed and the black smoke withered away and died.

Sherlock's immense relief was palatable in the rare ear splitting grin he gave Billy as he noted. "I'd say that our little test has proved conclusive." Clapping his apprentice on the shoulder he announced with renewed enthusiasm. "Now to get back so we can complete our task."

And with that he turned, belstaff flapping in the breeze as they headed triumphantly back to the others.