The saddest I've ever read
The Same River
because there are worse things than death. But there is also a superb plot, brilliant writing, deeply-felt love, a touch of irony and lines like these
He went to join Grey and they stood looking into the garden. The light was fading but the main features were still clear.
"You won't have seen real countryside, Grey. The whole of the island isn't like London, you know."
"No, Ray's started teaching me. See, there's a bird. And that's another kind of bird."
Doyle choked on his whisky. Maybe that waste was the main cause of Cowley's glare, more than the flaws in his teaching or the excesses of his laughter. With a struggle, he got himself under control. "I'm sorry, sir. But I think we've just heard him make his first joke. It's quite an occasion."
and to raise the spirits afterwards
because they are so B/D (although in this Doyle never was in CI5), there is first dislike, then friendship, lust, finally love (or at least the beginning of it), and pointed dialogue
At the end of that day, he spent a few minutes with Lucy updating his appointment book.
"Oh, he came back, you know. While you were with your three o'clock."
"What're you talking about?"
"That Bodie man. 'Smiler' I call him. Because he doesn't. He said ... um ... it had worked. But he hadn't realised till he was on his feet and moving around. And he paid."
"Oh." Doyle frowned. "He didn't make another appointment, did he?"
Lucy shook her head.
A broad smile. "Perfect."