"John, you're a man of science…?"

John looked up from his paper, surprised. True to his word at their first meeting, Sherlock hadn't spoken for two days. He had even warned John that he was going into a time of deep thought and contemplation of 'certain problems,' and that John shouldn't take it personally. He had moved about the flat—sitting at the table with his laptop (not John's for once),several books spread about with pieces of paper marking pages and lying on the couch with his long fingers templed in front of his mouth. John had made enough of a fuss about the nicotine patches previously that he had limited himself to just one, sleeves rolled up so that John could see proof.

John had gone about his own business, occasionally placing a cup of tea at Sherlock's elbow that was dutifully drunk, and waving take-away menus then ordering Sherlock's favorites for him. Sherlock ate sparingly, always with a book in hand.

"I think we've established that fact," John smiled.

"Of course, I just need…I need your opinion."

"Whatever I can do to help."

Frankly, John had been relieved that Sherlock had seemed so focused on this problem, whatever it might be. There had been no cases for nearly a month and after some weeks of a tetchy and tense Sherlock, silent and occupied Sherlock had been a relief.

"How would you make it look as though you were breathing out blue and white flame?"

"Not like fire eaters and fire breathers I take it?"

"I don't know. Fire breathers have a combustible substance that they blow out, but they need to have a flame to ignite the fuel. What if you had no visible flame?"

"I suppose that you could have some sort of mask that contains both the fuel and the flame. It seems like it would be very dangerous."

"Agreed. And added to that is the problem of the time."

"The time?"

"The mid nineteenth-century."

"What? What are you working on?"

"I'm trying to solve the mystery of Spring Heeled Jack. If I can figure out how he did it, I might have a better idea of who he was."

"You're trying to solve a hundred and fifty year old mystery that might have just been a hoax or mass-hysteria to begin with?"

"I was working on Jack-the-Ripper and Whitechapel murders and the Whitehall murder, but I can't figure out a motive on those, and without evidence I can't determine if the murderers in those made any mistakes. They always do, but the police, such as they were then, as you well know, are idiots and probably missed everything of importance. All that the reports talk about is the gore and the violence.

"I thought if I could figure out the identity of Spring Heeled Jack it might give me insight into the motivations of the nineteenth century criminal."

John laughed. "Don't tell me you're actually trying to solve all of the unsolved murders and crimes in history?"

But Sherlock had buried his face in his hands in agitation. It wasn't a joke. Or not to Sherlock.

"What kind of detective am I, John, if I can't figure out these ridiculous crimes when there should be so many clues? From a drop of water a logician could infer the possibility of an Atlantic or a Niagara without having seen or heard of one or the other."

John moved to Sherlock's side on the couch. "Now, now, they've puzzled experts for for over a century. It's not a failing."

"Hmpf, experts…" Sherlock snorted but he took a deep breath and leaned back against the sofa.

"It bothers you, doesn't it? Not being perfect all the time."

"It bothers you when things go wrong."

"When a patient is dying, when I couldn't save someone, but those are here and now. What you do now helps people even if that isn't why you do it. These people," John waved at the scattered books, "they're dead and gone."

"If I had a time machine I would take you back so that you could go down in history as the man who solved everything."

Sherlock laughed; his first laugh in weeks.

John gathered books and stacked them on the table and took a glance at the laptop.

"''Spring Heeled Jack was said to be tall and thin, with the appearance of a gentleman, and capable of making great leaps.' That could be you!"

Sherlock smiled. "Shall we conduct some experiments?"