There could be any number of locales where Charlie had ended up, and with London being quite expanse it could take days, no, weeks to search it all. For that reason Watson knew they had to start small, and what better place to begin their hunt than the place of residence? Not a moment after he had voiced the very idea did Holmes return to them, immediately showing there was no need for such an endeavor. Smiling exasperatedly the doctor let out a sigh, nodding to himself before glancing towards the windows. Of course there was no need, his companion could thoroughly inspect a home in moments and come up with information that a full force of officers wouldn't be able to in an hour. Just because the home itself proved to be devoid of any clues hardly meant their investigation was without promise; Holmes would find clues, of that Watson had no doubt, but now they would simply be outside of the home itself. The world outside was even harder to track and single out a single clue, or it would be if you didn't know what to look for. Footprints, the faint trails left by a cart's wheels, disturbed foliage, anything that might indicate movement could lead them to their quarry. Yes, the rainfall might obscure some of this, but you could not wholly eliminate every trace. 

Ever the gentlemen, Watson had offered his umbrella to Ms. Mortsan in favor of using it himself, wishing to provide however little comfort he could in these turbulent times. The doctor may have extended the same courtesy to Irene had she not brought one of her own, and if he wasn't still the slightest bit wounded over being swindled during their last meeting. The fact they were avoiding the road right away raised a number of alarm's in the good doctor's mind, and no doubt in Holmes' as well. If one kept to known paths then the likelihood of someone seeing something was greater, it was when you deviated and wandered off that things became more complex. Between the grass and the puddles of water it was difficult to spot anything whatsoever out of place, though again, there was plenty of searching to be done. Their walk would take them well off the beaten path, and interestingly enough to a manhole some ways away from the road. Mary had mentioned before that Charlie tended to take a different route, but he hadn't considered the sewers. For a man as cleanly as Watson such a route was... Well it was far from ideal. This was where their investigation would take them however, and reluctantly or not he would follow them into the depths. 

Of course Irene had come along, she just seemed to want to do so to bother Watson. Perhaps he was being a bit cynical, she did claim to be Mary's friend and could just as well be here to console her, should the need arise. Being the last one down into the sewers, Watson made it a point to close it behind them, not wanting to leave any indication they may be on someone's trail. Mercifully the sewers weren't nearly as rank as he'd feared, yet his nose still wrinkled in disgust simply at how unclean it was. Keeping well away from the water as he descended the ladder he glanced around, curious to see if perhaps there were any clues even here before they moved along. Seeing nothing out of the ordinary and noting no cause for alarm in Sherlock, Watson went ahead and followed after Mary, keeping an ear out for anything that might be cause for concern. "Yes, well... I have to wonder whether I prefer the rain, or the sewer," he replied lightly, smiling somewhat as he glanced down at the murky water, "At the very least I know the rain is clean."

Their journey to the outskirts of London had been every bit as brief as Mary had said, with only the sound of their footfalls accompanying them on the way there. When they had come to a standstill at the aforementioned ladder Watson opted to head up first, slowly ascending the ladder and taking a brief pause at the top; a carriage driving over it as he tried to uncover the lid would be most troublesome, best to be sure the coast was clear. That was providing they were even on a road, it could well be in an alleyway or behind a building for all they knew. Hearing nothing above the surface, Watson carefully balanced on the ladder and used both hands to push the lid up, sliding it to the side and climbing out. Sure enough they weren't quite on a main road, but rather one of the smaller, adjoining ones that led from the city to the storehouses and docks. With buildings obscuring most of the sky the rain was mercifully held back, only the occasional spurt of downfall making it through. Kneeling on the road above Watson extended a hand to the others, helping every one of them up and out before rising to his feet. 

"It's interesting... I've never really considered using the sewers as a means of getting about. At least... Not one's main means," Watson mused aloud, wrinkling his nose again as he caught a final waft of the sewers below. That might be perhaps due to the fact he would never in a million years consider doing it himself, only if his work were to take him there as it had now. With that painstaking leg of their journey done with they could focus more on searching for Charlie again, which while certainly more difficult was welcome. Taking a handkerchief from his coat pocket Watson wiped off his face, walking to Holmes' side and glancing both ways down the narrow street. "Well Holmes... Any thoughts?" he asked, glancing at his ever-diligent companion, "I'm sure something must be turning in that head of yours."