There's really no way to add spoilers to this one - the description blurb tells you most of what actually happens in the story.

But it doesn't explain the near-perfect build up of confusion from the two main characters as they try to make sense of what is happening around them, the outdoorsmanship they display that isn't full of author mistakes, and the timed blending of back story about how they became the best friends we see now as they navigate their crisis together