Sherlock gasped loudly and doubled over in his chair, gripping his arm tightly. "Sherlock?" John asked, peeking around the corner from the kitchen. "Sherlock are you OK?" The detective fell to one knee, his head resting on the coffee table and a choked moan escaping his mouth. "Sherlock!" John sprung up from the table, banging his shin so hard on the corner, that he was seeing stars by the time he reached his flatmate.

Sherlock's breathing was coming in ragged gasps, the constriction of his airway clearly audible. John tugged on the shoulder furthest from him, getting Sherlock to roll over so John could inspect him. The youngest Holmes fell like a sac of cement into John's lap. "John." He gasped in a small voice.

His eyes were red, and he was still gripping his arm. John brushed the hair from his face and felt the cold sweat beading the pale forehead, and he tried to sooth the shaking man. "Relax, Sherlock, I'm going to help you."

Sherlock slipped into unconsciousness, his hand fell to his side, and a syringe rolled across the floor. In a voice that could be heard through all of London, John bellowed, "MRS. HUDSON!"

As the clatter of heels on stairs began, John repositioned the detective onto the floor and began giving him emergency care. He listened for breathing, checked for a pulse, and yelled again for the landlady. Mrs. Hudson came running into the room, and John practically shouted, "Call an ambulance!"

His medical training kicked in right away, and he began his rescue routine. Thirty chest compressions, two rescue breaths. Thirty chest compressions, two rescue breaths. Tears rolled down his face as the reality of his situation set in. "If you die on me again, Sherlock, I..." He choked on his words, then silently continued the CPR.

Mrs. Hudson came back in the room, "They're on the way!" She looked at Sherlock and turned white. "Is he having a seizure?!"

"No, he's overdosed. His muscles are receiving too much stimulus. He's just trembling." John gave two more breaths, and this time, Sherlock began to breath on his own, but in ragged, short puffs.

Three more minutes of CPR later, the emergency medical technicians were clamoring up the stairs of 221B, loading Sherlock on a stretcher, and whisking him away. John tried to follow, but an EMT stopped him. "Sir, please give us time to do our job. You can follow up behind us."

John, though still worried and upset, was too exhausted to argue. He yelled after Sherlock that he would follow in a cab, and went back up the stairs to gather Mrs. Hudson. She was sitting on the couch, still white as a sheet. John put a hand on her shoulder, and she whispered weakly. "Overdosed? On what?"

John remembered the syringe, and scooped it up from the floor. He looked at it for a moment, then gripped it so tight, his knuckles blanched. "On this, damn drug!" He yelled through gritted teeth, and used his thumb to snap the needle in half. He threw the syringe onto the floor, the glass shattering. "I have to go." He rushed out of the flat and down to the street. Not bothering to hail a cab, he just took off running in the direction of St. Bart's.