If you're looking for a satisfying ending, pick another book. If, on the other hand, you're looking for a cliffhanger…
Pure is the first book in a trilogy, so you're not going to get a clean ending. In fact, the ending gives us more questions to ponder than we had before the last chapter. It seems like we will have a new character to think about in Illia, and what on earth is Partridge doing standing on that car? And why is something burning? What kind of mess did Partridge get everyone into?
The obvious answer is that the ending scene where Pressia smells smoke is just a lead-in into the next book in the series. But let's not stop there.
The main storyline in this book is that Partridge is looking for his mother, and Pressia is trying to escape the OSR. But this ending makes us pretty sure that Partridge won't be looking for his mother anymore — seeing that she's dead — and Pressia doesn't seem to care about escaping the OSR any longer. For the next book, we're left with the inclination that the group we've been following is going to lead some kind of a rebellion against the Dome. At first they were the prey, but now they're the predators. It's looking like the best defense is a good offense.