The book is Europe’s Last Summer, by David Fromkin. Here’s why: 
For some reason, I’ve become fascinated with the First World War — known aptly still as The Great War. Last year, I decided to create a timeline about it, and used a “timeline” from the Wikipedia (really just a table of events and dates) to build it. You can see it here in progress. This has led me to read a couple of books, including The Somme by Martin Gilbert, The Guns of August, by Barbara Tuchman, and others. But all along I’ve been bewildered by descriptions of how the war started. In all accounts, there has been a huge missing piece that no one is willing to admit was missing: The assassination of a major political/royal figure in the Balkans as a start to the war, despite being a casus belli, didn’t make complete sense, and didn’t seem to justify the war going from a local (and relatively common) Balkans war to a “world war”.
Fromkin, a professor at Boston University, does a splendid job of unraveling all the tangled elements — and introducing recently discovered events — of the “July Crisis” of the Summer of 1914, and makes real sense of it. The book is short and stays on its clear path beautifully. It seems like a missing key to any World History education.
This week, I’ll start adding events to my WWI timeline from Fromkin’s book, and will seek him out too for other ideas. Fromkin also wrote A Peace to End All Peace — another brilliantly elucidating book about the end of WWI and the formation of the Middle East: More on that book on another day.