After leaving the Yard, Sherlock and John slipped into a cab and had it drive them to a certain curb at Sherlock's orders. The two got out of the cab and John tossed a few notes into the passenger seat before jogging onto the sidewalk. Sherlock explained that just a block or so away from the official sewage system entrance was an alley which would lead to an old trapdoor.
"It used to be an emergency escape route to enter and exit the sewers. But near the 1990's it was shut off and barricaded since drug dealers and homeless people found their way into the sewers and started tainting the waters with natural waste and drugs. If my theories about Neo are correct, then the entrance should have been unlocked and merely covered up to avoid the suspicion." Sherlock stated flatly, and made his way down the pavement, John at his side.
"It's already 9. Neo should be in the sewers by now." John said, looking up at Sherlock. The moonlight shined down eerily upon the two as they walked down the block. No people walked along the sidewalks. The only signs of life were Sherlock and John, as well as the occasional car that passed by.
"Yes, I know. That's why we need to get in there quickly if we want to find anything," Sherlock noted, and hurried up his pace. The two turned the corner and into the alley, and immediately stopped. Just beside the entrance sat a hooded homeless man which held a suspicious bag of white powder. Sherlock pushed John back and disappeared behind the corner, his eyes wide. "Shit." He hissed, and John sighed heavily.
"Who knows how long it'll be until the bastard will leave?" John groaned. Sherlock shrugged and thought hard. After a moment or so of thinking, Sherlock's mouth turned into a smile of triumph. He looked down at an expectant John, a gleam in his eyes indicating that he's concocted a brilliant plan.
"John, do you have your badge and gun?" Sherlock asked, and nearly jumped with joy when his colleague hesitantly nodded.

"Are you sure this will work?" John asked for the fifth time. Sherlock adjusted his coat collar and nodded.
"Positive." Sherlock grinned and held his hand open. John pursed his lips and handed Sherlock his police badge. John pulled the gun out of his pocket and gripped it in his hands. Both took a deep breath and then sprung out from behind the corner and began to run towards the homeless man huddled near the entrance, whose nose was now brimmed with the white powder.
"THIS IS THE POLICE! DROP THE BAG AND PUT YOUR HANDS UP!" John shouted loudly, pointing the gun at the man. Sherlock took out the badge and flashed it at the man. Immediately, the man sprung to life and leaped upwards, stuffing the white bag into his tattered hoodie pocket. He raised his hands immediately but remained silent.
Sherlock and John approached the man, but his face wasn't visible. The taller buildings cut off the light from the moon, and the three men were in partial darkness.
"I-I didn't dooo anything, Mr. Policeman." The man whined, obviously high.
"SHUT UP!" Sherlock shouted, and the man stopped whining. John stifled a grin and cleared his throat, not lowering the gun.
"I'll give you to the count of THREE to give me the bag." John commanded. The homeless man didn't protest and pulled out the bag.
"Give it to me," Sherlock ordered, and the man quickly tossed him the bag. The detective caught it and stuffed it into his overcoat pocket. "Now get out of here."
The homeless man stared at the two men in disbelief.
"What?" He asked, unable to believe what Sherlock had said.
"You heard him. Get out of here, and stay away from this place. I don't ever want to see your face here again." John hissed. The homeless man stood still for a moment, hesitant, and took a step forward.
"ARE YOU WAITING UNTIL I CHANGE MY DAMN MIND?! GO!" Sherlock exclaimed. The man took off immediately, disappearing around the corner once he reached the end of the alley. Sherlock and John stood silent for a moment, and once there were sure the man had run off for good, they both burst into hysterics.
"That was GENIUS!" John laughed, gripping his sides. Sherlock smiled smugly and laughed as well.
"I told you it would work." The detective grinned. After the two flatmates recollected themselves, they sighed and let the laughter out of their system for good.
"Alright, back to business then." John said once he had recovered from the laughing fit. At the same time, his stomach grumbled with displeasure. "Dammit." The man groaned. Sherlock smirked and headed up the alley, towards the corner where they devised their plan. John followed behind, confused.
"Sam's Sub Sandwiches is just a few shops down. Go get yourself something quickly and meet me down here in 10 minutes again. I'll stay here in the meantime." Sherlock stated, pointing a slender finger down the sidewalk. John stared up at Sherlock with wide eyes. Strange that Sherlock, out of all people, would actually take time out of a case to let John eat. But John didn't question the detective and simply thanked him. He then took off, leaving Sherlock alone.

Sherlock leaned against the wall with his hands in his pockets, his back to the alley and the other half of the sidewalk. He watched as John ran down and came to the shop, finally disappearing behind the door. The detective then took it upon himself to think over the case and events of the evening. He then recalled he still had the bag of drugs in his pocket. The detective quickly took it out and stared at the half-full plastic bag. Sherlock glared at the contents under the light of the streetlamp, and felt his mouth drop open after realizing that the substance resembled something completely different than drugs.
Sherlock opened the bag and dipped two fingers into the powder. He took them out and rubbed the powder between his thumb and index finger. After feeling the roughness and texture of the powder, Sherlock's thoughts were confirmed. This was chalk, not cocaine or anything of the sort. Why would a person take it upon themselves to act high and pretend that they had a bag of drugs? Sherlock asked himself, even though he knew the answer. To distract you. Sherlock's eyebrows furrowed and he stared down at the package.
"Why distract us?" Sherlock asked aloud, knowing that there was no around to hear him anyway.
The detective motioned to slip the bag back into his pocket, but before he could have his arm was tugged back harshly. The detective shouted in surprise and felt a hand close around his mouth. Sherlock was pulled back into the alley, out of sight. The man was turned around and pinned against the wall by the throat. He dropped the bag and tried to make sense of what was happening. The arm pinning Sherlock against the wall slowly ascended, and the detective was forced to stand on his toes to avoid getting strangled completely. Sherlock strained his eyes to adjust and see who had confronted him. His vision finally cleared and his eyes got a view of his assaulter. It was Neo. Oh. That's why.
Sherlock grew tense and began writhing against Neo's grip on his throat.
"If you continue, I will kill you." Neo hissed, his voice cold. His eyes held the look of murder, and Sherlock automatically stopped moving, gritting his teeth to stop the screams building up at the back of his throat. "Good. Listen, Sherlock," Neo spat the name. "You've been showing extreme resistance to this virus, and the vaccination helped out. Now, if you're cured, that will ruin all of the boss's plans. And that can't happen. The only method left to get you out of the way is direct injection," Neo used his free hand to pull out a syringe from his front pocket. It was filled with a clear liquid that was faintly tinted green. "Don't worry, you'll just feel a slight pinch." Neo smiled darkly and raised the syringe until the thick needle was touching an artery on Sherlock's neck. The detective managed to scream, but he received a blow to the stomach from Neo's knee.
"JOHN!" Sherlock managed to yell. Neo scowled and kicked him again. The detective held back a shriek and shut his eyes in pain.
"I warned you once. This is the last straw. I will kill you if you don't shut up." Neo shoved the syringe roughly into Sherlock's neck. The detective squirmed in pain and discomfort, and received another painful kick, this time in the shins. Sherlock's clenched his jaw tightly. He felt the injection, the disease being pushed into him and his bloodstream. The sensation was sickening and the detective used up the remainder of his will to not shout for help. John. Help. Me. Sherlock pleaded internally, but he gave up for he knew it was too late anyway.
Just as quickly as it began, the injection ended, and Neo pulled out the syringe. He slid it back into his pocket, but still didn't release Sherlock. "The boss has snipers everywhere, and visuals in all the places you'd least expect. If you tell John, Molly, Hudson, Anderson, Donovan, or anyone else about this, you and everyone connected to you will be killed. You have my word on that." Neo finished, and pulled his arm away. Sherlock crumpled to the floor and gripped his own throat, breathing heavily. His mind span around wildly and he watched as Neo ran off, rounding the corner and darting down the opposite street.
Sherlock weakly raised himself and spat on the ground angrily. He began to regain his thoughts and senses, and he took a deep breath.
The detective turned the corner and leaned against the wall once more. A minute passed and John came out of the shop, smiling with satisfaction. He approached Sherlock and stopped in front of him.
"Thanks for the mild break, I really appreciate it." John said with a grin. Sherlock managed a weak smile. "Did anything happen in the time I was gone?" The doctor asked, his eyes curious.
Sherlock wanted to tell John what had happened tremendously, but he didn't take Neo's warning as a bluff and didn't want to end up killing everyone he knew by saying a mere word.
"No, nothing happened. Let's get going, shall we?" Sherlock said flatly, and turned into the alley. John followed behind him, completely unaware of the burden Sherlock now carried.