The first you may be familiar with, it is "The Rise And Fall Of The Third Reich" by William Shirer. An excellent book that is very thorough. Make sure you get the unabridged copy (over 1,100 pages) as it is far superior to the abridged volumes out there.
The second is Part 1 of Winston Churchill's The Second World War. It is titled "The Gathering Storm" and focuses on the peaceniks who continued to appease Hitler every step of the way. Everytime Hitler went against his word, these pathetic fools would continue to trust him. "This is the last time he deceives us," they would say, "Next time we will surely put our foot down." But it never happened until it was too late to stop WW2.