John should have realised that it was never going to be that simple. Despite the antibiotics, Sherlock's temperature remained stubbornly high, and his white cell count and CRP continued to climb. They were missing something, John knew it, but he just couldn't work out what it was.

Sherlock was being examined clinically twice a day, his charts analysed, his chest auscultated, his abdomen palpated, and still nobody seemed any the wiser. They had grown staph in his blood cultures too, and his antibiotics had been changed to those with appropriate sensitivities. It was being chalked up to a resistant sepsis, but John wasn't convinced. And every day, Sherlock grew a little weaker, and his renal function deteriorated a bit more until dialysis was beginning to look inevitable.

He was going to die, John knew it, but he was damned if he was going to let him go without a fight.

Sherlock knew people all over London, people who knew everything. What would Sherlock do, if he had somebody who was dying and he didn't know why?

He would call John. And if John couldn't or wouldn't help, he would call - Molly. Molly the pathologist, Molly who knew about death and what caused it, but more to the point who knew about diseases and pathological processes and how to think backwards to find the causative organism from the end result. Molly who might just be the only person who could save Sherlock.

'I could look at the central line?' She had suggested when John phoned her. 'See if I can get any other information from that? It's a few days down the line now, but I'm happy to look at the cultures, see if there's anything that they missed?' And his blood results - I could look at those too. I'll let you know if I come up with anything.'

'That would be great,' John said. 'But I was hoping for a bit more of a hands-on approach.'

'Meaning?'

'I was hoping that you'd come and examine him.'

'I'm a pathologist, John. My kind of examination usually involves a sternal saw.'

John winced. 'I wasn't thinking of anything that extreme. But an external examination. You could do that couldn't you? See if you can find any clues.'

'If you think it would help, but why would I find things that the intensivists haven't?'

'Because you know how to look, Molly. No, you know how to observe, as Sherlock would say.'

'How bad is he John, really?'

'He's bad, Molly. Honestly - I'm not sure he's going to pull through this one.'

'I'll be there in an hour,' she told him.

...

'So how do we do this?' Molly asked John.

'How do you normally do it?'

'Well, I normally start with the history, read the case file. I've already done that. Then I look at any results we've already got. Again, been through those. Then I expose the body and do a full external examination. Top to toe, front to back, look at every inch of skin, look in every crevice, every orifice, look under the finger nails, see what I can find.

'Then go for it,' John said, pulling the blind down over the door. 'Apart from the full exposure of course. I think we should do this in sections. Don't want him to get too chilly.'

'He's got a temperature of 38.5, John. Might do him good to cool down a bit.'

'Still,' John said. 'Preserving modesty and all that. Let's do it a bit at a time.'

They started at the top, Molly inspecting Sherlock's scalp, his ears, his nose, his mouth, as much as she could around the endotracheal tube and finally, removing the tape that held his eyelids closed to protect his corneas, his eyes.

'What are you expecting to find?' John asked fascinated.

'Anything really; Arcus; Kaiser-Fleischer rings, or - Oh My,' she murmured.

'What?' John asked.

'Look!' Molly said, flashing the pen torch at the corner of Sherlock's right eye as she held the lid open.

'There's - a red dot?' John asked. 'Could be anything.'

'Apart from it isn't anything. It's a conjunctival petechiae. And there's another one there - look!'

'Meaning?'

'Could be nothing. He's been ventilated, his platelets dropped for a while. Depends if there are more of them. Hand me that opthalmoscope will you?'

John did as he was asked, and Molly after examining the back of Sherlock's eye for several minutes, muttering to herself.'

'What is it?'

'He's got retinal haemorrhages. Lots of them, and - yes! That one's definitely got a pale centre. They're Roth' spots.'

'What?'

'Did you sleep through your pathology lectures at medical school, John? Roth's spots.

'Still not ringing any bells. Humour me.'

'Roth's spots. Retinal haemorrhages with pale centres, due to micro-infarctions. So - conjunctival petechiae, and Roth's spots. Let's see if there are any more.'

Molly examined every inch of Sherlock's skin. She found another cluster of petechiae on the sole of his left foot, and a small red nodule on the palm of his right hand over the thenar eminence, at the base of the thumb.

'I give up,' John said. 'What is it?'

'Oh come on John, call yourself a physician?'

'No, I call myself a surgeon, and occasionally a GP.'

'It's a Janeway lesion, John. Has he had an echo?'

'A few days ago, after he threw the emboli. They were looking for signs of right heart failure.'

'And they didn't see anything else unusual?'

'Not that they mentioned.'

'Then he needs a trans-oesophageal one. Hand me that stethoscope.' John did as he was asked, and watched as Molly listened to Sherlock's heart. After a few minutes of listening in various places, she grimaced and handed the stethoscope to John. 'To be honest, I'm not sure I'd hear a murmur if one was there,' she confessed. 'I'm out of practice. My patients don't tend to have heart sounds. If they do, then I get worried,'

John grinned at her, despite the situation. 'Call yourself a doctor, Molly?' he teased, extracting a little revenge for her earlier comments.

He started in the mitral area, as he had been taught, listening with both the bell and the diaphragm at the outer edge of Sherlock's healing left-sided scar, careful not to disturb the wound. First heart sound, second heart sound, no added sounds, no 'absence of silence'. It all sounded normal. Then he moved across, to the lower left sternal edge. First heart sound, second heart sounds, but then there was something else. A whoosh where the first heart sound should finish. A flow murmur from his fever, or the sound of a leaking valve? John couldn't be sure. He listened further up the chest wall - aortic area, pulmonary area, and in both he could hear the soft whoosh of blood flowing where it shouldn't.

'Listen to this,' he said, keeping the stethoscope on Sherlock's chest, and holding the ear-pieces out for Molly.

She listened, closing her eyes to focus on the sound, then removed the stethoscope from her ears and nodded at John. 'There's a murmur. Hard to tell where it's coming from with the noise of the ventilator, but there's definitely something there.'

'Why wouldn't they have picked it up?'

'We're old-school John; well, you're older-school than me, but we learnt clinical skills the hard way. Nowadays it's just whack on the bedside ultrasound and have a look. And they probably weren't looking at flow through valves. Even if they did see a bit if regurgitation, they'd likely chalk it up to a bit of pulmonary hypertension from the infection and congestion.'

'So fever and a new murmur, he's got endocarditis?'

Molly nodded again. 'With septic emboli to the lungs, because it's right sided, and very few peripheral emboli because they have to get all the way through the lungs first.'

'Molly, I could kiss you,' John said, giving her a hug instead, and kissing her on the cheek as a compromise.

Then he frowned. 'But why would he get endocarditis now? It's ages since he last used - must be two weeks at least.'

'It could have been floating around for that long. It's often insidious, remember? Or it could have started in here. The valve is damaged by the turbulent flow from the contaminants in the drugs - usually, it's the baking powder, or whatever they cut it with that does that damage. It's effectively like having a graze on your knee, but instead, it's on your valve, and the damage to the endothelium allows bacteria to settle and Bob's your Uncle, you've got endocarditis and you throw off clusters of bacteria to your lungs and that makes you -' she paused and stared at Sherlock as if seeing him for the first time, 'really, really sick,' she murmured.

'Get him a trans-oesophageal echo, John,' she said. 'As fast as you can. If it's not responding to antibiotics, he might need surgery to remove the valve. People can function quite well without the tricuspid, so they'd be better off taking it out entirely if it comes to it.'

'How do you know that?' John asked.

'Didn't I tell you? I wanted to be a cardio-thoracic surgeon for a while. Turned out I didn't have the temperament for it, but it's amazing what you pick up.'

'Anything else we should be thinking of?' John asked.

'Something you won't like,' Molly said.

'Go on.'

'That central line,' she said. 'I checked the lab results. They grew all kind of odd things from it, that they assumed were contaminants. Organisms that you just wouldn't find on an intensive care unit.'

Like what?'

'Mould spores for a start.'

'So?'

'So did he still have his central line in when he did his little bunk last week?'

'Yes.'

'I may be wrong, but I'd say that line was used somewhere damp, an old building in all probability.'

'What are you saying, Molly?'

'I'm saying that I think he shot up into his central line when he went AWOL. I think that's why he's got endocarditis and that's why they can't identify the bug. I think he's got a fungal infection on his heart valve.'

'They grew staphylococcus aureus,' John said,

'Which is a common skin commensal. Did they grow it in the cultures?'

'In two sets. The others have all come back as negative.'

'So either the staph is a contaminant, or he's got more than one organism on that valve.'

'So how do we find out what it is? They've done cultures every day Molly, he must have had ten sets by now. They've all come back negative apart from the two that grew staph.'

'Which would fit with fungal infection too. We need to get clever.'

'How?'

'We need to get a sample of whatever's causing this. I brought some kit with me.' Molly produced a carrier bag and emptied its contents onto the silver equipment trolley in the corner of the room.

'What is that?' John asked.

'Punch biopsy kit,' Molly told him. 'We're going to take samples of whatever is causing the infection from the site of the peripheral emboli?'

'Meaning?'

'The petechiae in his foot and the lesion on his hand. They're both caused by bits of vegetation breaking off the valve and shooting down to the peripheral circulation until they get wedged in arterioles. They should be teaming with whatever organism causes this. If I take a sample from them and get it back to the lab fast, I should be able to grow it, or identify it with PCR. The sooner we know what the organism is, the sooner we can get him on the right treatment.'

With thanks to my fabulous beta team of sevenpercent and ballierj.