Sherlock checks his watch.
He never needed one before, but it's difficult to deduce the time on the basis of changes in light and air quality when one is perpetually crossing borders: a different altitude, a different time zone every few weeks. He's been in Manila five days. If he's honest – and honesty is grim, but indispensable – it's harder than it was. Seventeen months stalking the shreds of Moriarty's network has ground him down to little more than dust.
John would laugh. This dried-up shadow, barely able to put one foot in front of the other, barely able to remember the day's details, never mind catalogue the soil types of whatever continent he happens to be standing on – John would laugh himself sick.
Another hour and he'll be on a boat to Macau; then overland to Hanoi, if he's right and that's where the target he missed in Bangkok has fled to. Mycroft will know.
It's not bottom, though: bottom was Amsterdam three months ago, when he punched the hotel bath mirror because a man in the café downstairs who wasn't John had laughed like him. But all the blood had reminded him, how John would have wrapped his hand in a towel and squeezed. He wraps his mind in that thought, both memory and promise: it keeps him homeward bound.