"Well, there goes one of the options," John said, smiling weakly.
He suddenly swayed violently, his knees buckling underneath him. Sherlock caught one of John's arms, easing him down to the floor gently. He turned to face the speaker, which was lying haphazardly on the floor near the kitchen. His look was scathing. John could barely keep his eyes open.
Sherlock got up and walked straight towards the speaker. He grabbled the cold, clammy mechanical device. "Now, you'd better cooperate with me. Do you understand?" Sherlock hissed.
"I understand, but that doesn't mean—"
"Trust me, if I had the time, I could easily concoct an antidote for whatever toxin you've injected, but I have neither the leisure of an hour nor the patience of a saint. You will tell me what it is you used, exactly, and I hand you over to the authorities quietly."
The speaker was silent. Then, quietly at first, the man started to laugh. The sound grew louder and louder. John winced on the floor in pain.
Sherlock's face went pale. He threw the speaker on an armchair, pushed up his sleeves, and crouched down beside John, who was curled up in agony.
"John, listen to me," Sherlock whispered, gripping his friend's shoulder. "I'm going to need you to do something for me. And I'm going to need you to trust me. Can you manage to fight through this for just a minute?"
John nodded weakly, his forehead burning up.
Sherlock put Mycroft's handgun into John's shaking hands. "John, look at me," Sherlock said firmly. John barely opened his eyes. "John, you've got to do this. You've got to pull the trigger. If I'm dead, he'll give you the antidote. Do you understand?"
"I…I'm not going to…" John struggled to say.
"John, this isn't the time to be a hero. Don't be an idiot," Sherlock said, his voice quavering a little. If John didn't know better, he'd think that Sherlock was afraid.
"And you're…an…imbecile…" John said. He laughed, but the laughing turned into painful coughing.
"John, if you trust me, pull the trigger," Sherlock said.
"Never," John replied.
"John, pull the trigger," Sherlock said, loudly.
"I…will…not…"
"JOHN, PULL THE BLASTED TRIGGER!" Sherlock roared.
A shot rang out.