Ah, a trilogy's middle book... By the nature of its position as #2 and in this case, the name of book three (Horde), you know how this is going to end before it begins. Outpost is the story of our young heroes attempting to integrate into life in the town of Salvation. Of course, you know that can't last. The mutants are growing in number, and getting smarter. An isolationist strategy can't last. As all things tend towards chaos, you know chaos is coming.
Outpost is a slow burn. There's no hurry to get to the end, but that's to be expected because while we know it's coming, the inhabitants of the town don't. Sure, there are alarming events that worry those who are paying attention, but it's not like they're bracing for the inevitable, because they've lived there for generations. I didn't find myself wanting to hurry it up because the story was interesting as our heroes grew, learned more about civilization, adulthood, and tested boundaries. The community also grapples with gender roles, religion and some of the societal norms. All while the threat grows.
When all heck finally breaks loose, it's not exactly a surprise, but it definitely makes sense. I have really appreciated that this author has really thought through the story she wanted to tell and mapped it out from end-to-end. And in some ways, by the time you get to the end of Outpost, things are just heating up.
Don't read the author's notes at the end, though. In her attempt to reassure you that she's thought things through I think she actually gives you a spoiler that you don't need.
Enclave (My Review, Amazon.com)