"Well, John, that's the crucial thing I have already pointed out to you a couple of times: When I've eliminated the impossible, whatever remains, no matter how mad it might seem, must be the truth."
"Ah, yes, I remember…" John replied weakly. "However, that would be really, really mad! - Assuming, you were right, when would he have done it?"
"Not recently. As I said, I knew the errand boy, but I didn't recognize him when he did his delivery, therefore, it has to have been done before! – Molly, we have to talk to Molly."
They grabbed their jacket and coat, hurried down the stairs and hailed a taxi outside 221B that took them to St. Bartholomew's through the heavy late morning traffic, both Sherlock and John lost in thought.
Molly was really happy to see them looking well. She started chatting about how worried she had been and how nasty it was that apparently the errand boy had accidentally switched Sherlock's petri-dishes with the ones from the children's gastroenterology lab. Oh, and she wouldn't want to imagine what it was like to have a Norovirus infection. Sherlock and John exchanged glances, trying to avoid laughing out loud.
Norovirus. That was what Mycroft had told her!? At least he could have chosen something less disgusting! Although, it had prevented anybody from wanting to visit them.
Molly danced around Sherlock excitedly, pointing out repeatedly that she was sorry for what had happened and that next time she would deliver any results of Sherlock's experiments personally, just to make sure they wouldn't be switched again.
John watched the scene in front of him with a smile on his face. To anyone else, Molly's crush on the Consulting Detective was so clearly visible. Only the object of her desire pretended not to notice, however, he knew exactly how to use her feelings for his own purposes, which he occasionally did.
Sherlock carefully probed into what else Molly knew. She explained that she had given the petri-dishes to the errand boy who did deliveries for them on a regular basis. She had been surprised, however, when Mycroft had paid her a visit at which he had told her about Sherlock and John's infection with the Norovirus and questioned her about how that mistake could have happened. The day after, when Molly had wanted to read the errand boy the Riot Act, he had already quit his job.
By flattering her, Sherlock forced the pathologist to do some phone calls to find out where the young man lived. He pretended to be wanting to personally "thank" him for weeks of diarrhoea and talk to him about his duties as a reliable courier.
After having got the address, Sherlock left instantly, leaving John to thank Molly and say good-bye. He caught up on his companion in the street, where he had already flagged downa taxi.
"Care to share your thoughts?" John asked cautiously, making himself comfortable in the backseat of the taxi.
"Hmm…. Not yet," the detective replied distractedly.
John shook his head in mild annoyance.
After some search for the apartment they were looking for they were invited in by the young man that had been the errand boy for Barts. Peter, as was his name, told them that he had changed shifts with some other errand boy who had phoned him to ask for that favour. Since he had had better plans for that day, he had agreed and stayed in.
Upon questioning him about the other errand boy, Peter said he didn't know him very well, no face, just a name, which wasn't unusual since there were many errand boys on odd jobs at Barts. He explained that the reason why he had given up his job was that he had a new one, better-paid, at a private firm in London.
Obviously the few questions they had asked were sufficient for Sherlock, because he suddenly stood up, thanked the young man and left the flat, John following him once again in a hurry.
"Sherlock, could you please fill me in? Were those all the questions you had?"
"It wasn't important what he said, it was important what he didn't say! He lied about the changing of the shifts. He was bought off. Didn't you see the new and very expensive mobile phone on his desk, the packaging still in the bin. How much money do you earn as an errand boy, eh? Going by the furnishing of his one-room apartment - scarcely any furniture, the meals that he had – mainly fast food of the cheapest kind, his long-overdue haircut, do you think he would be able to save that much money? There was still some money left in the envelope sitting under the cushion of his bed. He lied about the job, he doesn't have one. There was a newspaper with the odd job ads open, some circled. So far, so obvious. Assuming that he wasn't simply feeling like quitting his job, what – or who - made him? Did you see circles on the floor? Like dried droplets – or… like dents of the tip of an umbrella."
"Mycroft!" John exclaimed in amazement. "Do you think he paid him off?"
"No, no, no! That's not the way he does it. He wouldn't pay; he would scare the life out of him… or let him disappear mysteriously!"
"Well, he hasn't disappeared, so he's scared, do you think?"
"He is! Didn't you notice? He rubbed his hands dry on his jeans – a couple of times, his gaze was unsteady, at least very nervous, if not frightened."
"Sherlock, what I don't understand is why would Mycroft do this? I mean, he wouldn't kill you, would he? He actually helped to rescue you. That doesn't make any sense!"
"No, it doesn't, does it?" Sherlock was apparently as much at a loss as John.