Mission accomplished! Draft 4 is complete! It’s taken a month longer than I had originally planned but I’m there now, so who cares how long it took!
Structurally the second half of the book is quite different than it was in draft 3, shifting the focus onto the characters rather than the situation. As Steve Chambers told me recently: simplify the story, complicate the characters. It was very good advice and I’m happy with where the story is at now. My wife is reading it first, then it’ll be taken by a pincushion* of winged unicorns to my agent. Wish me (and the unicorns) luck!
*Collective noun for winged unicorns.