Writing a book part 21 - entering the home stretch?

After a slow month for the book last month (mostly due to Easter holidays) in which I just managed to finish chapter 20, I have now started chapter 21, which is the beginning of the denouement. Set mostly in Lisbon, it plays out the plot twist that is revealed at the part one, and also involves the main two characters establishing a relationship. This makes it quite complicated both in terms of plot and tone, and getting that right is quite tricky.

One of my main objectives is to 'show don't tell'. This is classic fiction-writing advice, whereby you reveal the story via actions and narrative rather than simply telling the reader what's happening. However, the difficulty can be to ensure that a reasonably nuanced plot remains comprehensible when trying to avoid explicit narrative.

I've been reading two books recently that demonstrate both ends of the spectrum. One was a popular but trashy cop thriller full of clunky dialogue in which characters explained the plot to each other, and where there is absolutely no subtlety or intrigue (telling); and another much more literary novel which requires much more attention and concentration because nothing is explained outright (showing). It can be hard to follow, but the second book is a much more satisfying read.

I also need to re-work the final five chapters because they contain details that don't quite fit with the rest of the book as it now stands. I need to decide what to do about a particular sub-plot and also change the way the main story in Lisbon pans out. I'm impatient to finish, but need to get this part right, so have got plenty to keep me occupied! I plan to finish up to chapter 25 by the time my summer break starts in July, then finish the final chapter in September.