Apart from ancient and medieval, it's one of my favourite periods in history. It was such a turbulent and intriguing period, but a greater understanding of WWII can only be found by researching the inter-war period, that's where you'll uncover most of what drove Europe over the edge.
I have many books on the subject, but I can only guess that Echo Jnr would rather sit through my recommnedations available on DVD, rather than tackle some of the formidable tomes I possess on the subject.
1. The World at War. This 26 episode compendium covers every theatre of WWII, and is widely aknowledged to be the leading televisual resource. It was made in the '70s and contains a capturing blend of historical narrative and witness testimonies from both sides.
Amazon link.
2. Conspiracy. This HBO/BBC collaboration can only be described as bone chilling. It's a dramatization of the infamous Wannsee Conference that delves into the psychology of Nazi officials involved in the "Final Solution of the Jewish Question" during World War II. To an outsider it appears to be a very dull feature. But once you actually realsie what's being discussed, and the clinical indifference of the Nazi officials, you'll spend half your time spellbound by the sheer evil on display, and the other half hiding behind the couch.
Amazon link.
3. Hitler: The Rise of Evil. This mini-series explores Adolf Hitler's rise and his early consolidation of power during the years after WWI and focuses on how the embittered, politically fragmented and economically buffeted state of German society following the war made that ascent possible.
Amazon link.