Max and Pip's son, Dylan, is seriously ill. When his doctors recommend transitioning to palliative care only, they both want the best for him, but they cannot agree on what that is. Since they cannot jointly make a decision, it is left to the courts. From that point in the narrative, the book splits in two, following the story as it would unfold from each course of action.
I've seen some other reviews not mentioning that last part out of some kind of misplaced desire to avoid "spoilers." It's not a spoiler when it's the major sales pitch being used for the book. I heard Penguin promote this one several times over the course of the ALA Midwinter meeting and they never once failed to compare it to a "Choose Your Own Adventure" book; it's like when people try to talk about We Are All Completely Beside Ourselves without mentioning that the narrator's sister is a chimp. Sure, it doesn't actually come up narratively until midway through the book, but it's on the flap and it's supposed to be the reason you pick it up.
Considering that the alternating narratives are the main draw of the book, they start really late. It's in the vicinity of the halfway mark before the judge makes the decision, and the timelines split. The bulk of the book is very much a standard issue-driven relationship fiction novel, in the spirit of Jodi Picoult. Once the timelines do spit, Mackintosh adeptly weaves the two together, with echoes of the same beats being played out in different lives. It shows great thought and great skill, but it still takes a lot of reading (in comparison to the overall size of the book) to get to that for which the reader is encouraged to pick it up.
Overall: B-
After the End will be available June 25.