The detective entered 221B and climbed the stairs to the upper level flat. As soon he as entered the door, though, he paused. After just a moment, he continued to casually remove his scarf and coat as he spoke in clipped tones to the shadows on the other side of the room.

"Professional assassin…semi-retired, but you like to keep your skills sharp…retained on an official basis, though, not freelance...not anymore at least. However, you are not here in your official capacity tonight. Therefore, you require my assistance on something that will probably require more brainwork than deadly force. Would you care for some tea?"

The shadows flickered briefly and a strong female voice sounded clearly in the empty room.

"How do you know that I'm not here to kill you?"

"If that was the case, then I would have been dead the moment I opened the door. You are not the only assassin I have ever met, you know…not even the first today. In fact, I had a family luncheon with one this afternoon…mainly because her husband insisted on it." He paused and sighed heavily. "Friendship apparently comes with certain…obligations."

A sound of amusement emanated from the darkness and the voice spoke again. "Your reputation precedes you, Mr. Holmes…and now I can see that my intel on you was quite accurate indeed. I've come to the right place…and to the right man." With these words, the shadows moved, the lamp was clicked on, and a fiery redhead in a form-fitting black jumpsuit was revealed. "And yes…I would love some tea."

...

Sherlock sat quietly in the darkness after his unexpected guest had gone to bed. She had resisted the suggestion of rest, of course - even though hard travel and deep undercover work with no backup had obviously taken its toll on her. However, Sherlock explained that they would put out feelers in the morning when his network of Baker Street Irregulars resurfaced from their various hiding places - and that there was nothing to be done until then. When she had reluctantly agreed, via a discreet sleeping powder he had slipped into her tea when he refilled her cup, he then pointed her in the direction of John's old bedroom at the top of the stairs. He knew that she would appreciate its easily defensible position, in case of trouble. Not that he was expecting any…but he had also not been expecting her, either.

He had not exactly told the truth when he said that there was nothing to be done until the morning. What he really meant was that there was nothing that anyone else could do but him. Therefore, while she slept, Sherlock combed through the extensive collection of mentally filed information in his Mind Palace looking for connections and answers. Meanwhile, the part of his brain that was not actively poring over the problem, replayed the conversation that he and his guest had shared earlier over tea.

"I know all about the obligations of friendship," she had explained. "In fact, my best friend, Clint, always wants me to spend time on his family farm. Do I look like a farm girl to you, Mr. Holmes?"

Sherlock's eyes skimmed over her tight outfit. He was not blind, so he noted her alluring feminine curves. However, he found both the telltale and the discreet weapon bulges located all over her person much more interesting. Overall, her style was very suitable for combat situations, but not so much for rural life. "Not at all," he agreed mildly as he continued to drink his tea.

"Yet, I go there anyway," she continued with a sigh. "At any rate, friendship is why I am here now, as well. Clint needs for me to pass on a message to another friend of ours... one who has been purposely missing for some time now. One who felt the need to…and I am sure that you can appreciate this, Mr. Holmes…disappear for a while. He normally moves around a lot to stay off of the radar. Unfortunately, he has disappeared a little too well this time. We were able to trace him to London…but no farther…and that's where I hope that you can help. This is your home turf, after all."

Sherlock considered her words carefully – especially her reference to himself. "I take it that we are looking for a person who is mistakenly no longer considered to be among the living?" he asked and she reluctantly nodded her head in agreement.

"It needs to stay that way, Mr. Holmes," she emphasized.

He nodded his understanding - especially since he knew very well that there were many advantages to being considered dead by most of the world. "And the message?" he asked.

"It's urgent family business," she responded vaguely. Sherlock just shrugged at that. He did not really need to know all of the details to realize that this was already an unusual and fascinating case.

"One last thing," he replied. "You should know that I know exactly who you are: Natasha Romanoff…aka the Black Widow. In fact, you have been quite the thorn in my brother's side more than a few times. I feel that I must thank you for that, by the way...it's most entertaining to watch him fume. He even sent me after you to gather intel once, you know. However, despite my best efforts, you managed to completely evade me in Kazakhstan. I have to compliment you for arranging that goat road block at just the right moment, by the way. It was quite the feat, I assure you…and it even made for an amusing debriefing once I was back in civilization again."

"Kazakhstan…That was you?" the woman replied and the admiration in her tone was evident. "You were very good and almost caught me a couple of times, you know. The goat road block was my last ditch effort to escape…without killing you, that is. I guess we were both very lucky that it worked, then. Even though now I realize that I might not have tried so hard if I had known that the famous Sherlock Holmes just wanted to talk to me."

Even if he was usually better at deflecting such reactions than the average man, Sherlock was almost speechless for a moment when he deduced that the Black Widow was actually flirting with him! He may not have had much use for sentiment, but the right kind of woman - brilliant, cunning, and tough - could still distract him. It was becoming more and more clear to him that she was exactly that kind of woman. However, her reputation was also implicit within her very code name itself: Black Widow. She knew exactly how to get men to do what she wanted them to do...and then discarded them...in one way or the other. Sherlock had no desire to become her next victim. Therefore, he quickly composed himself before she could detect the change and plowed on with the conversation. "However, despite all of that, you are now a legitimate Avenger. Consequently, I am left to wonder why you would come to me for assistance when you have powerful friends out there who are in a much better position to help you?"

"When you put it like that, it does sound strange," she explained. "However, since the person in question is technically dead…and is subsequently off of the map completely…this cannot become an official mission. In fact, the Avengers can't be associated with it in any way. Half of them…including Clint…are still in hiding after the prison break at the Raft..." Here she had to pause and laugh at the sudden glint of interest that appeared in the detective's eyes.

"The Raft?" he asked curiously.

"An underwater prison," she explained...as if it should have been obvious.

"Fascinating!" was Sherlock's only response as he set his tea cup down and leaned forward in an obvious show of interest to learn more. Therefore, the woman launched seamlessly back into her story.

"…and the other half have their hands tied now because of the Sokovia Accords. Even though I know that all of them would help us – despite our disagreements - they are watched carefully and now have to account for their actions to people who do not even know of the continued existence of the person we are looking for. Technically, that should include me, as well. However, I am on the books as being on vacation right now...so I have a little bit more wiggle room than the rest."

"The Sokovia Accords?" Sherlock needed clarification. The name sounded familiar but he must have deleted the memory as unimportant since he could not seem to pull up any mental details. All he could manage to remember was the image of a city hovering in the sky...and that the Avengers had been there, as well.

She nodded, "It puts the entire Avengers team, and well as any other registered enhanced or powered person, under the control and regulation of the United Nations."

Sherlock made a sound of disgust at that. "Being at the beck and call of the British government is bad enough!" he exclaimed. "I can't imagine the horror of having the entire UN in my business and telling me what I can and cannot do." He snorted. "Never mind…I can imagine it…and I think that you would have been better off staying on the wrong side of the law as a freelance assassin!"

Natasha spread her hands out in a sign of resignation. "It is what it is," she said pragmatically.

Sherlock looked at her closely before he nodded his head in understanding. "Alright then…tell me everything that you know about this person's last whereabouts," he prompted. He then sat back in his chair and steepled his fingers together in front of his lips. It was his go-to thinking position, plus a sign that he had decided to take the case...and that he was now completely invested in the outcome.