(I have reached the penultimate chapter of The Insidious Dr Fu-Manchu and our heroes are returning to the home of the missing-presumed-dead Inspector Weymouth where strange things have been going on.)
They arrive at the cottage which is under surveillance by plain clothes detectives, and Petrie makes sure they've drugged Mrs Weymouth so she won't wake. Smith smokes his pipe and we learn he's bad at it**. Petrie uses the time to write up some notes on Fu-Manchu, and comes up with this sentence : "Imagine a person, tall, lean, and feline, high-shouldered, with a brow like Shakespeare and a face like Satan, a close-shaven skull, and long, magnetic eyes of the true cat-green: invest him with all the cruel cunning of an entire Eastern race, accumulated in one giant intellect…"***
An owl hoots three times, which means something to Smith and then it's two thirty in the morning and they hear the bells of St Paul's, apparently, and there's a knocking on the door. Smith opens it. "It was a wild, unkempt figure, with straggling beard, hideously staring eyes." They begin to laugh. Sounds like me coming home after... oh never mind.
James Weymouth recognises him as his brother John, the Inspector Weymouth who vanished in the Thames fighting Fu-Manchu while the latter was holding a needle that turns people mad. I think we're all pretty clear on what's happened. They grab him, all five of them, and Petrie injects him with something that Smith asked him to bring (presumably a sedative; I don't think they have a cure for Fu-Manchu's serum). Weymouth is subdued.
Smith then questions the Scotland Yard messenger and discovers that "He" is arrested at his chambers. Petrie/Rohmer are a little coy about it here but it's Professor Monde, because there's no one else left in the story to arrest. Smith says "Come, then. Our night's labors are not nearly complete." No, because the final chapter awaits.
* I initially mispelt this as "booby" and very nearly left it in but eventually changed it. Keep it subtle guys. Fu-Manchu wouldn't make jokes about knockers and/or sea-birds.
** "At intervals of some five to ten minutes, his blackened briar (which I never knew him to clean or scrape) would go out. I think Smith used more matches than any other smoker I have ever met, and he invariably carried three boxes in various pockets of his garments."
*** From this it seems he's writing up Chapter Two (or possibly Chapter Eight which paraphrases this sentence). Better hurry up Petrie; there's only this chapter and the next to finish the first draft! He goes on to note that this was "the night upon which I had learned of the existence of the wonderful and evil being born of that secret quickening which stirred in the womb of the yellow races." I, um, don't quite know what to make of that.