Sherlock twirled John's abandoned pistol between his long fingers, trying to rid his mind of any unnecessary thoughts. Vaguely he heard John complain about there being no milk and the gentle thud of the front door. Milk wasn't important to Sherlock, he simply deleted it. He drank his tea without milk anyway. He was trying to enter his mind palace, the place where his thoughts presented themselves as a chaptered book that after a short glance told Sherlock exactly where he needed to look. He couldn't do it today and he wasn't sure why.

"John, do you ever need something really badly but can't get it?" He asked before remembering John had already gone out. So he was surprised when John's voice came from in front of him. "No. Why do you ask Sherlock?"

"Just a question."

Now that John was back maybe he would be able to figure something out. He was missing something, overlooking it completely.

"John."

"Yes."

"Have you ever bought a woman a ring?"

"What- Why would.. If you're trying to ask me something.."

"No, have you ever bought a woman a ring outside of proposing?"

"I don't think so, why?"

Sherlock opened his eyes, jumping from the sofa. He began pacing around the room with his hands clasped together.

"The corpse, she was wearing a ring. Expensive by the look of it, could have contained a diamond and could have had a high gold percentage. It wasn't on her wedding finger but judging from the clothes she wears and the style of her home she wouldn't go for a tacky sort of ring like that. Yet when the ring was removed you could see a slight colour difference in the skin-she never took it off. It was clearly given to her by someone she cares abou-"

"Where are you going with this Sherlock?"

"There was some sort of poisionous substance on the ring that would slowly infect her, getting into her blood stream. The man she was 'dating' must have been wearing gloves when he gave her the ring. There are only a handful of shops that would sell that style of ring. Call Lestrade tell him to check all the expensive jewellers." With that Sherlock flounced out of the room, his dressing gown whipping behind him. John looked half confused and sighed before sinking down into his armchair. He pulled his phone out and dialled Lestrade explaining to him, in a lot less detail, Sherlock's theory.

John hung up the phone and settled back in his arm chair, almost relaxed enough to fall asleep when, "Come on John, we're going out."

Sherlock had materialised wearing his signature coat and purple buttoned shirt. John heaved himself off the armchair knocking his tea over in the process. He groaned and bent down to pick it up.

"No time." Insisted Sherlock, pulling on his scarf.

"Bu-"

"Let Mrs Hudson clean it up."

"She's our landlady!"

"Cleaning up is one of her jobs, isn't it?" Sherlock replied looking at John with a confused expression on his face before spinning round and walking straight out of the door. John grabbed his military jacket and followed Sherlock, half jogging downstairs and out of the front door.

The stars were very bright out that night but it was freezing cold. John shuddered into his jacket, inwardly cursing his flatmate. "Sherlock, remind me again why we have to walk."

"I'm thinking John; I can't think properly in a taxi with someone wittering on at me."

John just grumbled to himself but then Sherlock continued with "Exercise is good for people. It's healthy."

"Are you calling me unhealthy?" John replied, a hint of venom lacing his voice. Sherlock stopped and turned to John bemused, "Of course not, you're very healthy and in perfect shape." He swiftly began walking again followed by John who was blushing for some reason.

Did Sherlock just compliment me, John pondered as they strolled along the London pavements. Before he had time to really consider the idea Sherlock had stopped and stepped sideways into a building. John followed his lead, sneaking through a maze of corridors till they found Molly.

"Ah, Molly," Sherlock said, "Just the person I need."

"What can I do, I mean what do you need from me? Why-"

"I need to borrow your microscope."

"Oh, um of course, yes, um. This way."

"I know where it is Molly, I have been here before."

"Uh, yes." She replied, looking visibly hurt at Sherlock's blunt reply. The 'amateur detective' sauntered off, leaving John with Molly.

"Do you want a cuppa?" He asked.

"Yes, that would be lovely." She replied, her face lighting up in a smile. They wandered down to the hospital café, idly chatting about work, cases, Sherlock and how they were feeling. John had just sunk into one of the seats with a mug of tea encased in his hands when Sherlock strolled through the doors.

"John, we're leaving."

"Already?" Molly replied, trying and failing to hide her disappointment.

"Yes, come on John."

"But Sherlock my tea."

"John, we have to go."

"Why?"

"Because I have finished what I need to research."

"What were you researching?" Molly asked, gazing intently at Sherlock.

"What sugar looked like under a microscope." Sherlock replied, flipping up his collar. John looked as if he would have a fit.

"You mean you dragged me all the way here to see how sugar looked under a microscope."

"Yes." Sherlock answered, looking as if it was the most normal thing in the world to trek across London for that meagre experiment.

"You could have done that at Baker Street!" John exclaimed.

"Of Course I could, but like I say, exercise is good for you."