Chance--picked it off the shelf out of many books that I own unread.

At 70 pages in with a limited memory of 1-3, I don't see it as being entirely backstory, but I might be in little position to judge that, and I think I'll be putting it aside until I read 1-3 again--which may be soon if I borrow 'em from my dad and don't get distracted by other books, else it could be far in the future. :)