Sherlock opened the email:

This amounts to everything that we are certain of regarding Jonathan Blake. Keep in touch. M

The attachment contained a full and detailed profile of Blake, including his name, his date and place of birth, his exam results as a teenager, his tax status, his parents… But there was no current photograph of Blake, the newest image was taken around 10 years ago.

"Argh, this is all trivial, it is of zero importance. Useless" Sherlock slammed his laptop shut and pressed his head into the palms of his hands.

"How can it be useless? It is pretty much a complete profile of Blake…" John practically scoffed back at the detective.

"Yes, and its irrelevant. Who cares what he got in his Geography A level? Would knowing your full history like this tell me how you would go about taking revenge on someone that had wronged you in the past? No. At best this information would help me to make an inference that maybe you would kill a person slowly and covertly because being a Doctor you have the knowledge how to. Or maybe you would shoot them dead, because you were a soldier and that's what soldiers do. Two contradictory theories, both of which would be false because I know you, and I know that you would cut that person off and sulk about how terribly you have been treated, considering that to be the crueller and morally superior route. So you see, a complete profile of you would be useless, this profile of Blake is useless." Sherlock practically spat the words out, and pressed his face even harder into the palms of his hands.

John remained still, he flexed his hand and did his best to suppress the rage that was begin to boil up in the pit of his stomach. It didn't take a genius to work out that Sherlock was suffering from a pretty serious migraine linked to his drug use. He was clearly stressed and exasperated at not being able to do the work that keeps his mind focused and his blood free of narcotics. Obviously Sherlock was never going to say any of this, he employed his usual tactic of being rude and harsh to those around him, insisting that their stupidity was precisely what was preventing him from making meaningful progress. Still, John was rather a sensitive soul, and being spoken to like that did make him feel angry, and hurt. He let out a controlled breath before retorting,

"Okay Sherlock, drink some water and take some pain killers for that migraine. Call your brother and tell him that the information he's given you is utterly pointless and start thinking about what information would be useful and how we might attain it. Because you're right. A profile of you would suggest that you were a genius, yet you still manage to think and act like a child half the bloody time!"

Sherlock remained still, he knew that John was right, just like he always was. He almost stood up to rip into his blogger, just to exert dominance, but John might leave. Sherlock, really didn't want to be alone tonight. The detective sat up straight and pulled his hands away from his face. "I don't want any pain killers, nothing legal that you would approve of would soothe my withdrawal. I'm sweating and mildly shaking too. I'll push through it, it's a savoury reminder that after the fall, there is a landing. A rough landing. The easiest thing to do is to medicate that landing with other drugs, but then that would spiral out of my control and I would be an addict, not a user. I need to know the extent of Blake's relationship with Moriarty, and then I can start to work out what his next move against me or Sherrinford will be. But I can't know that, not until he makes his next move. It's frustrating, he is one step ahead and there is nothing that I can do."

John said nothing, surprised and somewhat impressed at Sherlock's stark honesty and calm. He didn't know what to suggest, he was sure that Sherlock had solved cases in minutes when he had far less information than this. At that moment Mary appeared in the door way. She had gone upstairs to bed an hour ago, clearly she had heard raised voices and made her way downstairs to mediate.

"Assume Blake knows everything that Moriarty knew. It's unlikely Moriarty would share all of his ammunition with another, but if he thought that Blake may not launch his attack until after Moriarty had shot himself then-"

"Stop. After Moriarty died. Of course, he would have known he would die at the top of…." Sherlock tailed off but jumped up from his chair and began frantically searching for his phone, throwing pieces of paper off his desk to get to it.

"Sherlock what… what is it?" John asked his friend, whilst looking toward his wife as though she might know what was going on, she didn't.

Sherlock grabbed his phone, but it began to ring in his hand. He stilled abruptly, "Its Lestrade".

"Answer it, Sherlock" John gently encouraged his friend, who nodded and put his phone to his ear.

"Lestrade. Where? I'm on my way. Is he there? Tell him you've called me and he is not to go anywhere."

Sherlock hung up and looked to John. "4 ODs in the same place. Are you coming?"

John looked to Mary who glanced in the direction of Sherlock before she spoke. "Go, John. Sherlock, solve this before our daughter arrives. I'll be fine, Mrs. Hudson is just downstairs if anything happens."

Sherlock locked his gaze onto Mary, he nodded. Mary understood what Sherlock was trying to convey, she wasn't as adept at reading the detective's looks as her husband was, but she understood. He would bring John home safely, and he would solve this before the child was born. John turned to his wife and hugged her, he began to talk in hushed tones whilst Sherlock put his phone to his ear once again.

"Mycroft. Yes I know, Lestrade called, I'm on my way there. I think I have an idea, I'll know for sure after I've visited the crime scene. 8AM, yes." Sherlock put his phone in his pocket and began to pull his suit jacket on. He glided across the floor and began walking down the stairs, John kissed Mary on the cheek and did the same. Sherlock threw John his coat and picked up his own, without a pause even for breath he opened the door and stepped out onto the pavement. John jogged out to stand beside him, "Where are we going?" he asked his friends as a cab pulled up in front of them.

"42 King Edward's Avenue, Hornesy." Sherlock said to the cabbie as he climbed into the back of the car, "popular crack den in North London", he added as John pulled the door shut and sat down next to him.

"What idea have you had then?"

"You'll see for yourself, if I am right." This cryptic answer was the last thing that Sherlock said during the 25 minute cab ride.