' - erlock? Sherlock, can you hear me?'

Someone was shaking his shoulders lightly, making his head loll sideways onto his shoulder like a broken puppet. There was a heavy, aching sensation still clawing at his chest, and his hands felt much too big. He was vaguely aware of the rumble of a car engine; of anxious voices talking close by.

' - no idea what happened. We were walking back to Baker Street after the fire - he had been strange in the taxi, fell asleep, like I said - and then he just told me he had been drugged and that was it. He didn't say much before he passed out - something about not being able to feel his hands, but that was all. Oh, and he told me not to take him to a hospital, and to bring him to Baker Street. He said he had antidotes there.'

'Well, I can't say it surprises me,' said another voice, deep and grim. 'I'll bet you there are quite a few people out there who would like to see Sherlock Holmes incapacitated: all the people he's locked up, for a start.'

'Didn't lock them up,' Sherlock mumbled, his mouth seeming to find it difficult to get the words out. When he did speak, his voice sounded slurred, as though he was drunk. 'Merely provided...evidence. Didn't...take part in...locking up.'

'Sherlock!' The hands had seized his shoulders again, and he let out a low moan of pain as his throbbing head was jolted downwards. 'Oh, God, I'm sorry. How are you feeling?'

As the probing hands continued to grip his shoulders, Sherlock suddenly remembered that he had left his experiment - studying the use of electrolysis to isolate potassium - out on the table. He knew he shouldn't have gone to wash the flask before he had finished, thinking to return to it later, but he had been distracted by the fact that one of the eyeballs he had been boiling at increasingly high temperatures had burst. 89 degrees Celsius, he thought vaguely, making a mental reminder to note that down.

'Left my experiment out,' he muttered, not managing to muster the energy to open his eyes. 'Potassium isolated via electrolysis...should have done strontium... Mrs Hudson hates it when I leave my experiments out. Eyeballs burst at 89 degrees. Should have written it down...'

'He's delirious,' Sherlock heard John's voice say, slightly muffled as though he had turned away.

'What the Hell has that drug done to him?' the other voice said angrily. Who was it? It was too deep to be Mrs Hudson's, and besides, this voice was male. He tried to think, but his mind had been wiped blank.

'Try to stay conscious, Sherlock, alright?' John said, squeezing his shoulders. 'Don't fall asleep on me now. We need you to try and stay awake.'

'Hang in there, mate,' the deep voice said, and Sherlock forced his eyes open a crack, just enough to see the grey hair and lined, weather-beaten face.

'We have visual contact,' the man said. 'You remember who I am, Sherlock?'

Sherlock shut his eyes and forced himself to think, to remember. He tried to open the door to his mind palace, but the handle would not turn. He tugged and wrenched at it, but to no avail. He was trapped: locked inside his own head.

'Sherlock?' said the man, and he realised that he had covered his face with his hands and that his eyes were screwed tight shut.

'No,' he said finally. 'I can't - I can't remember.'

There was a silence, and Sherlock gritted his teeth, trying to ignore the waves of pain that surged through his head with every movement.

'I can't remember,' he repeated, and as he spoke, panic washed over him in a tide that pressed him against the door of his mind-palace, crushing his lungs in fists of iron. He tried desperately to control his breathing, to remain calm, but the water was rising up his chest now, the waves lapping at his chin even as he beat on the door with his fists.

'Sherlock? Sherlock, calm down, it's alright, we've got you.'

The hands were back on his shoulders, although he had still not raised his head from his hands. He was vaguely aware of the fact that he was trembling, great shivers wracking his body and making him draw his coat tighter around him. He felt so cold.

'We need to hurry!' he heard John bark, and the other man's voice responding, 'I know, I know!'

Lestrade, that was it, he remembered suddenly, thinking of the name next to the speed-dial on his phone. His first name had slipped his mind - Graham? Gary? - but at least he had that one, small victory.

'What was it? Needle? Dart?' Sherlock heard Lestrade's voice say sharply.

'Needle,' John said. 'Though how whoever it was managed to first of all get within close enough proximity with Sherlock to jab him, and second to get the needle through his coat, is anyone's guess. I would have imagined that Sherlock would be paranoid of anyone getting close to him anyway, and after what happened with the bonfire, you would think he would be, if possible, more cautious.'

'Oh, I don't know,' Lestrade sighed. 'What are his symptoms?'

'From what he's told me, headache, nausea, general numbness most pronounced in the hands, fever, and,' - Sherlock felt two fingers press against his inner wrist - 'yes, accelerated pulse. I just hope that he has the right antidotes at Baker Street, and that he'll be alert enough to tell us where to find them.'

Sherlock shifted slightly in his seat, gripping his hair with shaking hands. Why was it so cold? John had said something about a fever: perhaps it was that which was causing him to huddle into his coat to try and retain some warmth.

'We're almost there, Sherlock,' came John's reassuring voice from beside him. Through the comforting façade, Sherlock could hear the anxiety and fear that layered his words.

'Coming around to Baker Street soon,' Lestrade chimed in. 'And then you can tell us where to find -'

But at that moment, a pain so terrible and blinding that it seemed like an atomic bomb in his mind exploded in his head, and suddenly he was falling down, down, down into a black chasm of agony. He could hear John shouting and his name being called, but the comforting note was gone, replaced by sheer panic. He felt his head smash against the window; felt himself thrashing wildly, his limbs seemingly out of his control. He was hammering on the door of his mind palace, screaming to be let in, but the floor had crumbled away and he was falling again, rushing backwards, away from John's frantic shouts and Lestrade's curses into the terrible, crushing blackness.