Detective Conan is a manga that largely doesn't go anywhere.
I don't generally mind this. It's similar to its peers in other media in that way - sort of a gag-a-day but for mysteries. I get why it bugs some people, but I've never been bothered about it because I enjoy the mysteries. Still, sometimes it abruptly remembers it does actually have an overarching plot and makes some overtures toward moving said plot along.
And my favorite such development to date is the one in this book.
In this volume, we learn the allegiances of some characters who've been suspicious for a while, we learn more about some of the baddies and we even have a fundamental shift in not only how our heroes relate to the big baddie, but in how we view some of those baddies.
This is done with a dual narrative - one story following Mouri and Shinichi on a ship full of monsters - well, people who are dressed as movie monsters - and one following Ai , who's fallen sick, as danger converges on her. There's a tense standoff, discussions of the past and motivations, and one of the most brave things I can remember a character doing in a manga I've read in a while.
Ultimately, this doesn't END anything, not really. But it recontextualizes enough about the story that it makes this one of my favorite volumes in this entire manga to date.