Sherlock walked out into the night. That was an extraordinarily foolish thing to do. It could jeopardise the whole con. Damn it felt good though.

The following morning, Molly had had approximately 2 hours of sleep. She stared unhappily at her wardrobe of costumes, longing for some of her own clothes. She pulled out jeans, a t-shirt and a leather jacket. Ok, so they were all designer, but still relatively normal. In defiance, she applied no make-up and scrapped her hair into a ponytail. Shrugging on the jacket, she grabbed her least ostentatious bag and left the house.

An hour later, Molly could be found at the Camden market, sipping a too hot takeaway tea and browsing second hand clothes. They weren't even good enough to pretend they were vintage. The market was busy and it felt good to be anonymous. Just one of a large crowd. How had she got herself into this mess? Well, a certain curly-haired devil, of course…and she just couldn't say no. It was time to change that. It wasn't too late to pull out of this mess. Nothing of substance to the case had happened. Just some outstanding oral sex and a forever changed relationship, said some small part of her brain.

Molly was resolved then. She'd go to Sherlock, tell him it was all over, take a week's holiday, get her cat and her flat back, and then return to work. Real work. It was for the best. When she was feeling stronger, perhaps it would be time to consider a job change, maybe even in a new city. Sherlock Holmes was clearly a toxic influence in her life.

But first things first… She hailed a taxi and directed it to Baker St.

While they drove, she took out a notebook from her bag, intending to jot down a few points for her conversation with Sherlock. He was bound to have counter-arguments and she needed rebuttal. Hang on, she thought, what's this?

"This" was a small postcard in her bag. She hadn't put it there. The picture on the front had the crown jewels laid on a purple velvet cloth. Turning it over, she saw a vivid green ink had written

"so you like diamonds?"

Underneath, printed as part of the card, were the words "bespoke diamonds" and an image. It was the back of a head with a tonsure cut into the hair.

FUCK, she thought, and then she said it again out loud.

Her taxi driver, a turban-wearing Sikh, looked in his rear view mirror askance.

"Sorry, terribly sorry. I just realised something important," Molly said hastily.

He nodded and returned his full attention to the road ahead.

Well, best laid plans…

There was still an out of course. All Molly need do is roll down the window and casually throw this car out onto the road. No one would ever know. She'd be back home by the end of the day. She looked out the window. They were nearing Euston Station. She had at most 10 minutes before arrival. She drummed her fingers on the arm rest. Was it too late? Was she in danger if she not now play along til the end. Was the Monk someone who also killed or was he purely a thief? Why hadn't she asked these questions in advance.

She looked at the card in her hand and at the window again. Dare she throw it out? Yes, but her conscience would niggle: not just about the contact, even the littering would bother her.

As fate was deciding for her, the car pulled up outside 221B. Molly paid the driver, tipping well to apologise once more, and got out. She rang the bell. For a long couple of minutes, there was no answer, and then Sherlock himself came to the door. He looked surprised to see her, and she in turn was surprised to see him holding Toby, who meowed in delight at the sight of Molly.

"Molly, what are you doing here?"

She pushed her way past, scooped up Toby and headed up the stairs without a word. Sherlock followed.

In the sitting room, Molly shucked her soft cream leather jacket and sat on the couch, petting the purring cat.

Sherlock entered the room. He opened his mouth to speak but Molly held up her hand.

"I came here to tell you I'd had enough of this stupid façade, Sherlock. A month of nonsense, and last night, last night was the final straw."

"I apologise for last night," he replied, very quickly.

"For which bit are you sorry, Sherlock? The kissing in the taxi? The oral sex in the kitchen? The leaving?"

"All of it?" his voice rose at the end, indicating how unsure he really was.

Molly shook her head, and ploughed on.

"I found this in my bag though."

She held out the card for Sherlock to take. His eyes crinkled at the sides as he read the brief message.

"This is fantastic, Molly! He's made contact. I didn't expect this so soon. Tell me everything. Where did you get this? Did you see the delivery person?"

"I was in the Camden market. It must have been slipped into my handbag."

"That means you were followed! And you were dressed like this, no make-up?"

"Yes, I came straight here, as I was planning to tell you I was done. I only found it in the cab."

"Yes, yes, you mentioned, but you realise it's far too late to pull out now, don't you?" Sherlock gripped her by the shoulders and looked her straight in the eye.

"I realise that. But there are new rules. I don't want to see you. Be the very model of a neglectful workaholic husband. We will communicate only through Anthea, or John."

Sherlock looked like he had comments but wisely kept them to himself, and nodded his agreement.

"Fine. Molly, I want you to go home now and do some online research."

"What?"

"Do some googling about diamonds. Famous diamonds, etc. Look at some diamond jeweller websites. That kind of thing."

"Ok, but why?"

"If he's following you, he's probably tracking your phone and computer. We've deliberately made them vulnerable to hacking. Oh don't worry, your preliminary work on the pathology in tv shows – great idea by the way – is safe. Wendy backed it up to a flash drive when she was cleaning."

"There's a lot more to her than meets the eye, isn't there?" asked Molly.

"Yes, now go. And thank you."

Molly gave Toby one final stroke and rose to leave.

After Sherlock watched her leave in another taxi, he called out.

"John, it's safe now, she's gone."

He turned around to face a very angry looking doctor.

"I don't know where to start, Sherlock," he said, furious.

"Oh I thought you'd want to go with oral sex."

"Sherlock! This is serious. What the hell are you playing at? Molly isn't some toy to be batted around. She's in real danger."

"I know. Why do you think I was with her last night?"

"Ha! Sounds like you needed an entirely different kind of protection. I thought the plan was neglecting her?!"

"It is, but part of that play is to occasionally spoil her, so that it looks like we have a guilt-driven relationship. The Monk needs to know that Harry Pearson would do anything to keep her on side."

"And exactly how does you-know-what come into it?"

"Well, that just sort of happened," said Sherlock, quite sheepishly.

"HOW DOES THAT JUST HAPPEN? I really hope you didn't learn this one on YouTube as well!"

"Nope, learnt that one in the usual way," replied the detective with a smile.

"And I left before it went any further," he added.

"You left? You complete tit! You can't just leave after that," said an exasperated John.

"Why not? I admit it was a personal challenge….it wasn't reciprocal you know."

"Oh god, Sherlock, stop talking. Immediately. I feel like we've had this conversation before but at the risk of repeating myself. You cannot toy with that poor woman's emotions like that. It's bad enough that you're playing fake house with her…but physical contact has to end."

"I already agreed to that, didn't I? You heard the whole conversation."

"Yes, but I am reiterating it. It's not fair. She likes you, maybe even loves you, and this is what, your idea of thanks?"

"Right, of course, because it couldn't possibly be that I like her too and got caught up in the pretending?"

"No. Wait. What?"