Six months later - September

Sherlock pointed at the pale, sweaty, morbidly obese woman in the consulting chair. 'You have five minutes,' he said. 'Go.' He checked his watch.

'There's a ghost in my bedroom,' she replied immediately, without any hesitation and in a tone of supreme assurance.

In the opposite chair, John snorted. 'Who are you going to call?'

Sherlock gave him a blank look. 'The police? I hardly think so.'

Their client gave John a vacant look. 'A medium? I tried that. She said it was the ghost of my sister.'

'And do you have a sister?' asked Sherlock, ignoring John's distraction.

'I do,' she said.

'And is she dead?'

'She is. But she wasn't green.'

John interjected again, to very little purpose, in Sherlock's view. 'You're being haunted by a green ghost and you don't know who to call? Come on – hasn't anybody else heard that before?'

Sherlock frowned, indicating to John to shut up. 'I haven't. And I don't think this is a moment for levity, do you? Miss Stoner has lost her sister. How exactly did she die? You have two and a half minutes.'

'She was murdered.'

Sherlock sat back in his chair, adjusting his mental stopwatch to account for John's interruption. 'Go on.'

'It was a dark and stormy night.' Helen Stoner licked her lips, glanced briefly around the room and sat forward. 'The day before my sister's wedding.'

John held up a hand. 'If I could just stop you there. What time of night was it? Exactly?'

'Three o'clock.'

'In the morning?'

'The afternoon.'

'Alright. It was a dark and stormy afternoon. How stormy? A light drizzle? Bit of a shower?'

'It wasn't stormy,' she clarified, taking a long slurp of the Coke she'd brought with her from the waiting room. 'It was a sunny day. Middle of the afternoon two months ago and the weather was about the same as it is now. I was sweating like a pig.'

'Excellent,' said John. 'I'm glad we got that straight. Carry on.'

'We were on a hen do, just me and my twin sister Julia. She was marrying Stephen from the supermarket, do you know him?'

'One minute left,' Sherlock intoned. 'And I only need the relevant details, not every single thought that crosses your mind.'

'We'd caught the bus into London, it was a big day, you know? She'd just come into some money, quit her job as a cleaner and she was really looking forward to the wedding. She'd bought a massive dress.'

Sherlock cleared his throat.

'Anyway, we'd been drinking for a while when Julia said she was hungry, so we looked for someone nice for afternoon tea, posh-like, I thought I'd treat her.'

John said, 'Tea at the Ritz then? Claridges?'

'No, the Krispy Kreme shop on the high street. So, we were eating and Julia had just started her fourth doughnut when it happened. She grabbed at her neck like this.' Miss Stoner demonstrated for at least thirty seconds of her allotted time, making gagging noises of surprising authenticity. 'Then with her last breath she said it. The sprinkled brand. That was all. Then she stopped breathing. They called the ambulance of course, but it was too late. She'd been poisoned.'

'Poisoned?' John repeated incredulously. 'I thought you said she choked to death on a doughnut.'

'Well, that was the mystery,' Miss Stoner responded. 'She only ever ate plain doughnuts, the glazed ring ones, but because it was a special occasion and I was paying, she went a bit wild. She chose one of the chocolate ones with the sprinkles on top, and that's what killed her. Whoever planted it in the shop must have known we were going to come in and injected it with arsenic.'

Sherlock sighed. 'And the ghost?' he asked, to cover the last few seconds.

'Comes into my room in the early hours of the morning. I hear a metallic noise, like a bell ringing, which wakes me up, and I have a sense that someone else is in the room with me. Once I managed to flick my lighter on just at the right moment and I saw the edge of its dress disappear under the bed. It was green.'

John made a point of looking at his watch. 'Well, thank you so much for your time, Miss Stoner, but I think your five minutes are up.'

Sherlock raised a hand, no more than mildly interested, which was much more engaged than he'd been in any other recent case. 'You have a ground floor flat,' he said, since it was patently obvious. 'Do you sleep with the windows and doors closed?'

She nodded. 'Helps with my asthma.'

'Then go home and wait for us, where is it you live?'

'Stoke Moran. Closest stop is Stoke Newington on the overground, or you can get the bus.'

John waited until she'd left the room before complaining. 'You're taking the ghost case? Even though she's a liar, a fantasist and probably never even had a sister in the first place. You'll take her case, but you won't do the one about the treaty that Mycroft has been asking you to look at for months? I don't understand you at the moment. I really don't.'

'Ah – thanks for the reminder.' He took the phone from his inside pocket and sent a quick text to his brother. Too busy to find your treaty – where was the last place you remember having it?

Then he yanked down his sleeves, flung on his coat, despite the heat outside, and made for the front door, flagging down the next taxi. It pulled up outside Helen Stoner's house in Stoke Moran long before the woman herself could possibly have made the journey by public transport. Sherlock took one look out of the cab window and leaned forward to issue another direction. 'Back to Baker Street, please.'

'What?' John yelped. 'Already? We haven't even got out of the cab.'

'No need. Look at the shop next door.'

John squinted out of the window, read ''Roylett's Exotic Pets'. And?'

Sherlock leaned his head back against the cracked leather. He had tired of lengthy explanations recently, chafing at the need to constantly slow himself to the pace of the people around him. No one understood, not any more. He closed his eyes.

'In the window of the shop you will notice two animals, a large stuffed cheetah and a baboon, which, added to the name of the shop indicates there is a reasonable likelihood they also sell small exotic animals such as venomous spiders, scorpions and snakes. The placement of Miss Stoner's front door in the middle of a terrace of commercial establishments indicates the premises must be above the row of shops, in this case directly above the pet shop. She keeps her doors and windows closed, there is no chimney in this building so whatever is entering her room must be coming in through a vent or along a pipe, which explains the metallic sounds. It must be small and capable of squeezing into tight spaces. Given the colouring she described, the only logical assumption is that a snake has escaped from the pet shop and is most probably seeking out the warmest place in the building, which is either in or underneath her bed.' He opened his eyes again, leaned forward. 'Baker Street please.'

'No, no.' John stopped the cab with a tap on the window. 'She has a venomous snake in her bed and you're going to leave without so much as telling her?' He shook his head in obvious disapproval.

'I don't do missing pets cases.' Sherlock was unmoved.

'You used to.'

'One,' he corrected. 'I did one. Once.' It was a time he looked back on with shame and resentment. 'If you want to go and tell her you've solved the case, be my guest. You could start a new blog: John Watson – pet detective. I'm busy and I have proper clients waiting.'

John opened the door and then stopped, shaking his head. 'You've changed,' he said. 'And I don't like it.'

Sherlock simply slammed the door and the cab accelerated away. He was scraping the bottom of the barrel, client wise, he knew, investigating anything that appeared to be out of the ordinary. After six months in which every other lead had been exhausted he was now reduced to following up fake ghost cases in the hope they might yield a clue. He expelled a long breath, tried to concentrate on the queue of people who would inevitably be waiting for his services back in Baker Street. But with John out of the way his thoughts turned in the same direction they always did.

Irene's flat.

It called to him in a way that nothing else had ever managed – sweet and alluring and very, very dangerous. No matter how hard he tried to get away, it always drew him back. He told himself he'd see a few more potential clients first and then, if it looked like nothing promising was going to come up, he'd go round.

The stopwatch in his head began ticking off a countdown.

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