Kate arrived at the crime scene just before eleven, summoned by a text from Sherlock, 'At crime scene, join us there after work?' Intrigued she had agreed, and somehow after a ten hour shift found herself walking up to the flashing lights in a quiet residential street not far from the hospital.

She gave her name to the police officer stationed at the the tape outside the house, and was let through. Trying to look as if she attended murder scenes every day, she walked into the house, and showed her hospital ID to the CID officer inside the front door. 'Kate Watson,' she said. 'Sherlock Holmes asked me to come.' The officer looked confused. 'Lestrade,' she called, 'Someone here to see the freak.'

Kate tried not to smile. 'You must be Sally Donovan,' she said.

'Yes, how did you know?'

'Stab in the dark,' Kate said.

A solidly built, affable looking detective in his late forties came down the stairs and shook hands with Kate. 'Greg Lestrade,' he said. 'Sherlock said he'd asked you to come. If you don't mind putting on a forensics suit then I'll take you through. I presume you're not squeamish about dead bodies?'

'I'm an A&E doctor,' Kate said darkly, pulling on the proffered suit, 'I've seen a lot of dead bodies, and quite a few severed limbs. It takes quite a lot to make me feel squeamish.'

Lestrade looked vaguely impressed. 'Fine, come on through then. Oh and just don't touch anything without wearing gloves.'

He led Kate through into a living room, where Sherlock Holmes was standing thoughtfully in a corner, looking at a woman in her twenties, who was lying face down on the floor. Blood was matted in her blonde hair and she was very much dead.

Sherlock looked up as she came in. 'Ah Kate,' he said. 'I need a fresh pair of eyes, tell me what you see.'

So this, then, was Sherlock in work mode. Kate walked up to him and kissed him on the cheek. 'Hullo Sherlock, lovely to see you too. Now tell me why I'm here?'

As she kissed him he turned his head and the upper part of his body towards her, instinctively, like iron filings redirecting along a magnet, his eyes lingering for just a second too long on her face. A casual observer might not have noticed the interaction, but John noticed and smiled to see his friends distraction. Lestrade also was not entirely oblivious to it, but was unsure as to its implications. His eyes darted between Sherlock and Kate as he considered.

Kate noticed too, and stifling a smile she deliberately walked across the room to the other side of the woman. Sherlock followed her progress with his eyes. 'Sherlock,' she repeated, amused at his reaction to her. 'Tell me why I'm here.'

He started, 'Sorry, got distracted. I need a fresh viewpoint. Tell me what you see.' Another test then. Fine, this Kate could deal with.

'Okay, young woman, probably mid twenties, lying facedown in a living room which is obviously not hers,' she said contemplating the scene.

'Why do you say that?'

'Shoes,' said Kate, as if it was obvious. Nobody would wear shoes like that,' she indicated the girl's designer shoes with her head, 'on an expensive carpet like this. If it was her own house she would have taken them off in the hallway before coming into this room.'

He nodded. 'Its not her house, although there are other ways to make that deduction. What else?'

'Well, she's lying facedown, which would indicate an assault from behind, but the head injury is unlikely to be the cause of death. She pulled on a pair of gloves from a box on the coffee table. Can I touch her?' she asked, looking at Lestrade.

'Please,' said Lestrade, intrigued.

'She has a laceration over her occiput, but its already partly healed, although it may have re-bled when she fell, hence the blood in her hair, and the wound has been sutured with - thats odd.'

'Go on,' Sherlock said.

'Its been stitched with silk, 0-0 Mersilk by the look of it, the sort of thing I would use to tie in a chest drain, never to stitch skin.'

Sherlock looked slightly perturbed by this new information. 'You didn't notice that?' asked Kate.

'A suture is a suture to me,' Sherlock said with a shrug. 'John said that it was unusual, but that people used different materials'

Kate shook her head. 'Nobody I work with would use silk to stitch a wound. Prolene or vicryl yes. This is the sort of thing that a vet would use.'

'So what you're saying is that somebody non-medical, probably a vet, stitched her head up - how many days ago?'

'Three or four I would say, looking at the wound, but they knew what they were doing. The sutures are even, well-spaced, and the wound edges are well-opposed. Its not a botch job, but I would say done by somebody who isn't used to treating people. Could she work at a vets, have hit her head there and they sutured it to save her a trip to A&E?'

'It's possible, we don't know who she is at the moment, but we can check local vets to see if anyone knows her, or if anyone is missing.'

Kate rapidly inspected the rest of the woman. 'No obvious neck trauma, no blood anywhere else that I can see, she must have fallen forward fairly quickly, she didn't have time to save herself. She pulled up the sleeves of the girls top after a nod from Lestrade. 'Here,' she indicated a mark on the upper arm. 'Puncture mark, that would fit with being injected with something that made her fall.' She glanced up at Sherlock who was looking nonchalant. 'You've already see this, right?'

'Yes, but I'd be interested to hear your theories,' he said, holding her gaze for just a second too long again. Kate had to look away first, but not before she had noticed Sherlock's lip curving upwards slightly, amused at her discomfort, and by the situation. Good to know that they were both finding this forced formality challenging.

Clearing her throat she tried to stay focused. 'Let me think, so you've got a head wound sutured with silk, most likely by a vet several days a go, and a murderer who has access to sedative and potentially lethal drugs, that would tie in with a vet wouldn't it? If you're trying to find a single unifying cause for all of her symptoms.

'Ochams's razor,' Sherlock said, with a smile.


'Which is the same conclusion that we'd come to from the injection marks. There are animal hairs from several different animals on her coat too, which would fit with her working at a vets. Anything else you can tell us?'

'Give me a minute.' She looked at the girls shoes, took them off her feet, inspected the label and the underneath of them, then looked at the labels on her clothes. John and Sherlock watched her with amusement. Finally she straightened up.

'The shoes must have been a gift, they're Jimmy Choos, you're talking serious money. The rest of her clothes are cheap. The shoes must have been a recent gift, there's still part of a barcode inside one of them. I don't know if shops use individual barcodes, but is there a chance you could track down where she bought them from that?'

'Its a generic bar code,' Sherlock said, 'So no help there. We didn't pick up on the discrepancy between the clothes and the shoes though, thats worth considering.'

'Thats because you're boys,' Kate said gravely. 'As long as you have clothes to put on you don't really notice what they are. So present maybe? The shoes I mean.'

'Expensive present, so a lover maybe, that fits with our original theory. She was obviously lured here for some reason. Dressed up like that? Presumably to meet a man. The man who bought her those shoes I would imagine.'

'Who is a vet?' Kate asked, seeing how this worked. 'The same vet who stitched up her head, the same one who killed her?'

'Possibly,' Sherlock said, 'but lets not jump to conclusions. What else can you tell me Kate?'

She met his gaze and this time held it, trying to work out what he wanted from her. 'Thats pretty much it, I think,' she started to say, then realising what he was asking softly said, 'Oh, that.'

She hesitated, and he uncharacteristically picked up on her discomfort. 'Lestrade, could you give us five minutes?' he asked.

'Just don't wreck my crime scene,' he said. 'I'll be next door when you're finished'

Sherlock pushed the door to behind him. 'It doesn't work like that, Sherlock,' Kate said quietly. 'You know that.'

'Try Kate, please.'

John looked confused and opened his mouth to speak. Sherlock raised a hand to silence him.

Kate knelt down next to the girl, looked at her face, and considered.

She looks - happy,' she said, 'not afraid. I know that facial expression can change after death or as a result of the drugs that she was given, but that would fit wouldn't it? She must have been coming towards someone who was already in the room, someone she was pleased to see.'

John still looked confused. 'Empathy?' he asked Sherlock, 'Is that what you thought Kate could bring to the investigation?'

'Partly,' Sherlock said, 'although it would seem that it works better with the living. Kate picks up on emotion better than anyone I've ever met. I wanted to see if I could use that.'

If Kate Watson was disappointed in his explanation for her presence, she didn't show it. She smiled at him, despite her best efforts to not distract him from the work at hand, and his eyes told her everything that she need to know. This time they both looked away at the same time. Focus, Kate, she thought. Exchanging meaningful glances with Sherlock Holmes wasn't going to help with the case at hand.

'There must have been two of them then,' John said slowly, turning round to look at the room properly, tactfully ignoring the interaction between Sherlock and Kate this time. 'Thats what we're saying yes? So the person that she expected to see, the one that she presumably arranged to meet was in front of her, and a second assailant, who then came from behind to inject her'

Sherlock nodded. ' Exactly,' he said. So,' he began to pace around the room, focusing on the body on the floor, speaking very fast, 'She came here to meet someone, probably a man; someone she was pleased to see, says a relationship; in a house you rent by the night, says an affair. Someone who could afford to buy her expensive shoes, says someone with money, presumably an older man.'

'Head wound stitched several days ago, probably by a vet suggests that she worked with him; also statistically many affairs occur between colleagues. Her clothes suggest a low paid job, receptionist or veterinary nurse probably. Now why would he want to kill her, or didn't he? He was in front of her,' he moved to in front of her head, 'so someone else was behind her,' he indicated to John, who moved to her feet, standing a few feet from the floor-length curtains. 'Probably hiding behind the curtains, so she wouldn't have known have known that they were there, its possible that even he didn't know that they were there. The murderer then came out from behind the curtains and injected her before she had time to turn round. Someone used to giving intramuscular injections then, either a powerful sedative, or more likely something more lethal. The murderer knew that she was coming here to meet the other person and wanted her dead, says a wife. So we're looking for a husband and wife team of vets, with a pretty young blonde receptionist or veterinary nurse, probably the latter given the animal hairs on her clothes; cant be too difficult to find.'

'Impressive,' Kate said, 'now, if there's nothing else you need me for, I'm going home.'

Sherlock looked up in surprise, 'You're not coming back to the lab with us?'

'No. Tempting as an all night session with you and John sounds, I have to be at work at eight tomorrow, and unlike you I do need at least some sleep'

Sherlock nodded thoughtfully 'Okay, but take this', he took off his scarf and looped it, still tied around Kate's neck, 'its cold out there.' She smiled at his thoughtfulness, aware that Lestrade was still glancing at them intermittently from the other room.

She kissed him swiftly on the cheek, 'Night, Sherlock, see you tomorrow. Good night John.'

'Goodnight Kate, see you soon.'

She went back into the other room to take off her forensics suit, leaving John and Sherlock talking animatedly in the other room. 'So how exactly do you know Sherlock?' Lestrade asked her as she took the suit off and put her coat back on.

'John works with us in A&E sometimes,' Kate said evasively. 'He thought that I might be able to help with some of the trauma aspects of their cases. He's a little rusty now he's mainly in General Practice.'

Sally glanced at her sharply, considering repeating her standard warning about Sherlock, but something in Kate's eyes made her realise that this would probably be ill-advised. 'Will you be okay getting home?' she asked instead.

'Yes, fine thanks. I'm only a couple of stops away, and the tubes are still running.'

As Kate walked towards the tube station, Sally asked softly, 'Now how on earth does a girl like that end up tied up with those two?'

Lestrade chuckled. 'That Sally, unless I'm very much mistaken,' he glanced at the next room to make sure Sherlock and John were still occupied and dropped his voice to a whisper, 'is Sherlock Holmes' girlfriend.'

'The freak has got a girlfriend?' Sally's voice was raised slightly in her incredulity, despite her attempts to keep it quiet. 'You're not serious. What makes you think that?' Every other detective in the room was suddenly listening to their conversation, while trying very hard to make it look as if they were otherwise occupied.

'The fact that he looks at her as if she's something to eat,' Lestrade slowed down for effect, 'and that she's wearing his scarf.'

Four people shot past him to the door to watch Kate walk down the street, trying to work out if the scarf round her neck was really Sherlock's.

Sherlock and John turned round to see what the commotion at the door was. 'Everything okay in here?' asked Lestrade, coming back into the room, trying hard not to laugh at his team's reaction.

'Yes, just about finished' said Sherlock, tapping away furiously at his mobile phone, then holding it up in triumph to reveal a picture of the dead girl from a facebook page. 'Clare Brett, works as a veterinary nurse at Tower Road Veterinary Practice in Balham. Having an affair with this man, Stephen Harris,' he navigated to a staff picture on the practice webpage, and indicated a middle-aged man in the middle of the picture, with Clare Brett clearly visible on the edge of the group. 'His wife, on the left in the picture, found out about their affair, somehow got into the house before they did, hid behind the curtain and injected Clare Brett with a lethal drug before she had time to realise that anyone else was there. There's an out of hours mobile number on the website. If you phone it I'm sure you'll be able to track them down without too many problems.' Looking at his watch he said, 'I think that just about wraps it up. John, I'll see you at the lab at 9am sharp, and we can tie up the loose ends and check the post-mortem report when it comes through. Goodnight all' and he swept out of the door.

'Share a taxi?' shouted John after him. 'We're going in opposite directions' replied Sherlock without turning round.

John shook his head, exasperated by his friend as always.

'Right, well I'm heading back to Baker Street' he said. ' We'll be in touch in the morning'

'John, wait,' said Lestrade. 'What happened to Sherlock's scarf? He had it when he came in, and now he is uncharacteristically scarf-less.

'I couldn't possibly comment,' said John

'And Kate Watson?'

'Is a friend' said John. 'Goodnight,' and he walked off towards the tube station to avoid further questions.

Kate arrived back at her flat twenty minutes later to find a tall, thin figure in a dark blue trench coat leaning nonchalantly against the railings by her front door. Cab, of course. That was how he had beaten her back.

'Now what on earth, are you doing here,' she murmured, kissing him on the cheek for the third time that night. He turned his head, so that the kiss hit the corner of his mouth. Kate allowed her hand to linger on the back of his neck for longer than she meant to, despite her best intentions.

'I can't come and see you?' he asked.

'Not when you're in the middle of a case, no. The work comes first. We agreed that.'

'The case is solved,' he said calmly. 'We know how, we know why, we know by whom. Lestrade and his team can do the rest, all that remains is to tie up some loose ends, and I can do that later.'

Kate narrowed her eyes and looked at him appraisingly. 'Sherlock Holmes, if you think that you can come here, have your wicked way with me, and then go back to the lab for the rest of the night then you've got another thought coming.'

'And if I was to come here, stay the night, walk you to work in the morning, and maybe even buy you coffee on the way, then would that be acceptable?'

'Perfectly' she said, laughing as she let him in.