He opens his mouth, ready with a slightly dry response, but he pauses, stunned at the scent. He hasn't smelled it for some time, but it's one of those things that never leaves him: pungent, slightly sweet, a smell of medicine and illness, a smell that lingers in dens of iniquity or the more clinical morphine.

It's a smell of his own illness, and that of others.

Watson steps a little closer. "We have no river here," he points out.