I'll be completely honest - I've become rather jaded with the whole angels-among-us theme, and have generally lost patience with the concept of dead loved ones watching over us. It's a story that's been done to death, and usually with such heavy-handedness, and such intimate ties to matters of faith, that I lose interest long before the end.
Imagine my surprise, when Probability Angels turned out to be, quite possibly, one of the most original additions to the theme that I've read it many years. It's definitely not an easy read, either in terms of the telling or the ideas within, but it's a rewarding one . . . provided you're not so tied to those aforementioned matters of faith that you can't allow of an entirely new and different philosophy.
Here, the dead are not so much loving protectors, but curious souls who have been rewarded for their selfless choices with an eternity of . . . well, call it human experimentation. Alone, and emotionally disconnected from their memories, these probability angels make it their mission to find human beings with the potential for greatness, to analyse their possible futures, and to then push them towards the one they feel best serves humanity. Think of them as the forces of fate, but with a bit more backbone, and little regard for their target's happiness. It's an unsettling idea on several levels, and one that's not without its flaws, but it makes for an engaging story.
As you might expect from the title, it's also a book that's liberally sprinkled with mathematical and scientific concepts. Rather than drag the story down, though, they add something new to the telling, taking the place of the more generic spiritual metaphors and similes. It's a book that forces you to step back from the page and think on a regular basis, one that raises the questions, but doesn't necessarily give you the answers.
The second half of the book stumbles a bit, sacrificing the novelty of the opening chapters for a more generic good vs evil storyline involving angels and zombies, but not so much that it kills all momentum. It's still a great story, full of equal parts inspiration and entertainment, and the ending (while it may not be to everyone's tastes) completely lives up to the promise of the original concept.