In the train on the way to Aldershot, Sherlock Holmes expounded the theories.

'So what do we know? We know that Major James Richardson was in Afghanistan for a reason. We know this not just because he was an MI6 officer, and would not have been deployed there lightly, but also because he was only previously deployed there six months previously. Military Personnel are generally only deployed every two years, medical personnel for perhaps three months a year, but it would be rare to be deployed twice in such a short period of time. Therefore there must have been a mission, but it is a mission which is missing from MI6 records, or rather that has been deleted from MI6 records. I have asked Mycroft to attempt to discover what that mission was, for some reason he is disinclined to let me question MI6 or GCHQ agents.'

'The only clue that we have is the interpreter. James Richardson had a conversation with him that was nothing to do with medicine. If one had information for the other it seems unlikely that this was their first interaction. We need to know the extent of his acquaintance with the interpreter, and what they were talking about that led to Richardson's assassination.'

'But why would the interpreter tell him something and then shoot him?'

'He wouldn't thats exactly the point, haven't you been paying attention?

John Watson looked confused. 'The interpreter didn't shoot him?'

'Yes of course he shot him. We've got ten witness accounts that say exactly that, the question is who made him shoot him?'

'No, you've still lost me. Someone made the interpreter shoot him?'

'Precisely. Its unlikely that Richardson was giving the interpreter information, Yes? Far more likely the other way round. The interpreter was giving him information, but it was a trap.'

'If it was a trap, why couldn't the interpreter just have shot him?'

'Because if he did, why shoot the interpreter so quickly? Why not take him for questioning?'

'He had a gun in a room full of medical personnel.'

'He had a gun in a room full of soldiers, many of whom would also have had guns. The gun was a revolver, not a rifle. He used three bullets on Richardson, he only had three left. What would you have done in that situation?'

'I would have given him time to surrender.' John said slowly.

'Precisely. Only one shot was fired, by an infantry soldier on guard duty. The question is, why did he fire?'

...

Arriving at Aldershot they presented their ID to the guard booth and were waved through. Pre-approval had its benefits it would appear, although John reflected that doing it the legal way was somehow less satisfying than their normal methods.

Less than an hour later and Lieutenant Jones was being escorted into the room. He saluted the senior officer in the room, before he had even had time to take the proffered seat, Sherlock had shaken his head and said, 'No.'

John looked at him in surprise, Sherlock indicated the door with his head. 'A moment, please,' he said, walking out of the room with John.

'Ghurka, John,' he said as soon as the door shut. 'Thats why it took a while to find him, yes? Their base is in Hampshire, a short distance away from here.'

'And the fact that he's a Ghurka means that he couldn't have done it?'

'They're virtually incorruptible, John, you know that. Look at their motto 'Better to die than live a coward,' Thats why Prince Harry was imbedded with a Ghurka regiment in Afghanistan, because they're incorruptible.

'So Lieutenant Richardson wasn't involved?'

'Almost certainly not. And what kind of name is Jones for a Ghurka anyway?'

His father's, it turned out. His father who had died when he was two, prompting his mother to return home to Nepal where here son, much taller than the average Ghurka, but still with the same code of honour as all the rest, had eventually joined the Ghurka regiment and ended up back in England, the country of his birth. He had been briefly seconded to an artillery regiment for a period of guard duty, not a ghurka regiment, hence the confusion.

The interview revealed little more than his statement. He had known Major Richardson only vaguely, from the guard duty. He had found him to be amiable, but reserved. He had never noticed him talking to the interpreter before that day. He had never met the interpreter before that day.

Sherlock held up a finger, 'So he wasn't the normal interpreter?' This was new.

Lieutenant Jones shook his head. 'No, the usual one was sick, this guy was covering.'

'Had you ever seen him before?'

'No, never.'

'Why did you shoot him?'

'Because I saw the look in his eye. Desperation. I've seen that look on people's faces before, suicide bombers mainly, just before they pull the trigger. When you see that look on a man's face you either shoot, or you run for cover. He wouldn't have stopped until he ran out of bullets.'

'But he only had three bullets left,' John Watson said.

Lieutenant Mills shrugged. 'I didn't know that. He could have had another gun, he could have had a suicide vest, I wasn't going to take the chance. He'd just shot a British Officer and I had a clear line of site.'

'So you took the shot,' Sherlock said.

'Exactly,'

They watched the door until it had closed behind Mills, then Sherlock banged his hand on the desk in frustration. 'Ghurka!' how did we not know that.'

'So he wasn't involved after all, he was just acting to protect the medical team.'

'Obviously.'

'So we still don't know why the interpreter shot Richardson.'

'Frustratingly, not.'

'So what now?'

'Now we go and find out what we can about the interpreter.'

'In Afghanistan? You're crazy, Sherlock, you really think they're going to let you go out there, even with Mycroft's clearance?'

Sherlock gave him a withering look. 'Video conferencing, John. There's technology enough in Camp Bastion to mean that we don't have to go out there. They can bring the interpreters family and friends to a videolink there. I'm sure Mycroft would love to assist us. You head to Frimley and see what you can get from the rest of the medical team.'

Little, it turned out, but John duly interviewed all of them and recorded the interviews for Sherlock to review later.

...

Back at Baker Street, they compared statements with the 'team photo' of the medical team deployed to the warehouse on that day. 'There's someone missing,' Sherlock said. 'This nurse,' he tapped the photo to show a picture of a RAMC nurse in her late twenties, blonde hair pulled back in the pre-requisite bun.

'Off sick,' John said, 'I was coming to that, PTSD apparently from the events of that day and other things that she witnessed. She didn't have much luck apparently, two weeks later she was in the vehicle behind a tank blown up by a roadside bomb.

'Was she now,' Sherlock murmured, 'and she presumably got off without a scratch? How many lives does the average soldier have, John, more or less than a cat?'

'You think that she was involved?'

'I don't believe in coincidence, besides, look at her face.'

'I presume you're not interested in the perfection of her bones structure?' John asked.

Sherlock gave him a scathing look, and didn't bother with a reply. John looked closer, blowing up the picture on the computer screen. 'She's not smiling?' He ventured.

'No, she's not. What is she doing?'

John squinted at the picture. 'She's looking at something away from the camera, something just to the left and down slightly.'

'Who took the picture?' Sherlock asked, 'Who else would have been in the room.'

'The guards, and the interpreter.'

'Precisely, and out of those, who would have been superfluous to requirements, who would you have asked to take the picture?'

'The interpreter, so she was looking at...'

'His right hand pocket yes. If he was right-handed that's where he would have kept his gun, yes?'

'Yes, so she knew he had a gun. And' John was talking slowly, thinking as he went, but she didn't say anything because..'

'Because she already knew, but was checking that it was there, precisely.'

'So you think that she was involved?'

'Oh I think that she was probably behind it.'

John looked at the photo again, trying to work out if this pretty blonde woman could have orchestrated the murder of an army officer that she worked with, a doctor that she worked with, and then walked away calming psychological distress.

'But why? You don't think that she was involved with the insurgents, surely.'

No,' Sherlock sighed with frustration, 'I think that unfortunately its going to turn out to be a little more boring than that, how disappointing.'

'You've lost me,' John said. 'You're saying she had him killed, why?'

'The oldest reason of all,' Sherlock said, 'Passion. I don't think we're going to need that video-link after all.'