Sherlock lay on the sofa, enjoying the rush that came with a newly applied nicotine patch. The flat was quiet, just the way he liked it. On the coffee table before him was scattered some photographs, documents and evidence bags from the latest case Inspector Lestrade gave him in an attempt to pick his brains. It was not a very interesting case, in Sherlock's opinion. Man discovered burnt to a crisp inside a locked room. There were so many locked-room mysteries; surely the police would know better by now.

He clasped his long fingers over his chest, closed his eyes, relaxed and began thinking of other cases of spontaneous human combustion. His reverie was disturbed by the front door. Someone was knocking. He heard his landlady Mrs Hudson bustle over to answer it. He could not hear what was being spoken but the tone suggested that it was someone familiar to her. She and the visitor conversed in the entrance hall for a few moments – clearly, the person was not here to see Mrs Hudson.

The tread of footsteps sounded on the stairs, firm and unhurried. The tap of heel against wood indicated shoes with higher heels – a woman then. The swish of fabric with each step – a woman wearing trousers, cotton or something equally light. He detected a whiff of perfume mixed with chemical disinfectant as she entered the room and paused at the doorway.

"Hello, Sarah," Sherlock greeted without opening his eyes or moving from the sofa.

"Hello, Sherlock," Sarah replied. "I'm here to see John."

Sherlock gestured languidly in the direction of John's room and heard Sarah's footsteps move in that direction. "John?" he heard her call. "He's not here, Sherlock," she commented.

"Well, that would explain why I've been having such a pleasant and tranquil afternoon," Sherlock noted levelly.

Sarah re-entered the sitting room and leaned against John's armchair. There was a rustle of a plastic bag that she set down on the floor. "Are you going to tell me where he is?" she inquired.

Sherlock sighed and opened his eyes to look at his visitor. He glanced at her for a moment before resuming his contemplation of the ceiling. "Yes, I believe he mentioned something about going to his sister's."

"Right," Sarah nodded in begrudging agreement. "Must have completely slipped his mind that he was supposed to meet me then. He's been doing that a lot more lately. We used to talk but…" she trailed off.

"Come to think of it, John's been unusually reticent recently," Sherlock commented. "He used to be extremely verbose, especially when it came to discussing you."

"John talks about me with you?"

"He doesn't so much talk 'with' me as 'at' me," Sherlock pointed out.

Sarah moved to take a seat but she did not sit back in the chair. Instead, she perched at the edge. She leaned forward and surveyed the mess on the coffee table. "What are you working on now?" she asked.

"Dull case," Sherlock told her. "Man burned to death inside a locked room. Tragic accident."

Sarah picked up some of the documents for a closer look. "The police report says it's suspected foul play."

"Clearly, they're wrong," Sherlock declared. "He was trying to have a smoke inside his non-smoking flat. He shut all the doors and windows so the neighbours wouldn't notice. He settles in with a few drinks and his cigarettes. Then he passes out in the middle of his smoke and the embers fell onto his clothing, which proceeded to catch fire. He was obese so when the heat cracked open his skin, the flames reached the fat and he lit up like a human wick.

"No murder. Just a cigarette gone wrong. Someone must have told him smoking kills at some point," he added in amusement.

Sarah looked at the photographs and frowned. "He was certainly a big man but I doubt he was obese. In fact, I doubt he had much body fat at all. Look at his bones. The size and density suggests someone heavyset and athletic. Also, look at the way his body is positioned. It looks like it was placed there rather than a person sitting naturally."

"Are you saying I've got it wrong?" Sherlock asked, pinning her with an accusatory gaze, a hint of annoyance in his voice.

"I'm just giving you my opinion as a doctor having a cursory look at these bones," Sarah replied mildly, putting up her hands in a gesture of surrender. "I'm no forensic pathologist so there's no need to take my word for it."

Sherlock finally got up, snatched the documents from her and laid them back out on the coffee table, his mind racing over the possibilities. He could accept being wrong, but first he had to review the evidence again to see if the new theory fit the facts. His usual consulting doctors, John and Molly, were not available to him at that point so he had to rely on Sarah, who, if he assessed her correctly, was a perfectly competent family physician.

"Have you had much experience with bones then?" he asked.

"Well, I am a GP," she replied. "I've seen my fair share of broken bones. Especially from men who think they're tougher than they really are."

"And you think our man was one of those? Perhaps mixed up with the wrong crowd and suffered the consequences?"

"I have no way of knowing," she conceded.

There was an awkward pause as both Sarah and Sherlock pondered through their own thoughts. Then, in a voice that sounded too casual, Sarah asked: "Sherlock, did John talk about what happened in New Zealand?"

Sherlock did not look at her but remained focused on the documents as he replied. "He may have mentioned something." Sarah continued to look at him expectantly. "Something about a falling out," he finally added, looking at her reluctantly. "I wasn't paying strict attention at the time."

"You're not paying strict attention now," Sarah muttered to herself. "Do you happen to have any thoughts on the subject?" she asked.

Sherlock was surprised. "You're asking me for advice on your relationship with John?"

"Well, you seem to be able to read situations fairly accurately," Sarah said. "And since you're John's flatmate and friend, I thought he might have confided in you."

"I'm flattered that you think so highly of me," Sherlock said. "But I'm afraid I must disappoint. I have no insight to offer that you might find useful."

Sarah smiled politely. "Well, I guess I should go then. Good luck with your… case." She gathered her things and stood to leave. She made it to the doorway before turning around. "None at all?" she asked disbelievingly. "You, of all people, have no opinion to offer at all? I find that incredibly hard to believe."

Sherlock sighed. He stood and walked towards her, grasping her gently by the arms. "Oh Sarah, Sarah," he began. "If you truly want my opinion, here it is: It's never going to work out. You may both have a passing fancy for each other but the fact is, you're here and John's not. He seems to have forgotten he was supposed to meet you, and, according to you, this isn't the first time it's happened.

"You're here trying to mine information from your partner's flatmate instead of asking him directly. You may be spunky and smile and pretend everything is alright but it's all contrived isn't it? You and John are both play-acting at being a couple. Inside, you're tired of chasing after him and being someone you think you should be. You already know this. You realised the incompatibility in New Zealand, didn't you? That's why you had a falling out.

"The both of you want it to end but neither of you is bold enough to make the move," he concluded. He stopped and gave her a friendly squeeze. Her expression of horrified shock was expected. "I hope that was enough insight for you."

"Is that what you really think of my relationship with John?" Sarah whispered.

"Yes," he answered. "You asked and I answered truthfully. I don't beat around the bush and I would never lie to you, Sarah." He released her and took a few steps back, placing his hands in his trouser pockets. "I'll tell John you stopped by."

Sarah wordlessly nodded and left the flat.

After she left, Sherlock slowly peeled off his nicotine patch. It was starting to wear off anyway. He stood over the coffee table and surveyed the evidence. Finally, he reached into his trouser pocket and pulled out his mobile phone. He dialled a number, which was answered on the third ring. "Lestrade? Sherlock Holmes. I was wrong. It was a murder."

THE END