You will find a lot of extremely interesting information in this book about little known aspects of WWI. However, you probably need to be pretty familiar with the war or else it becomes confusing. This comes across as 3 books in one. The first two books were the most successful but the last one updates the story to the present day.
1. This explains how oil became such a strategic commodity in WWI. The British began to find tactical and operational advantages in a fleet running on oil instead of the traditional coal. The downside was the UK had large coal reserves but virtually no oil. The Germans found similar issues, so the race was one to secure oil in the Middle East and Caucasus. The Brits were more successful so the last 1918 German offensive ground to a halt in part to no fuel.
2. The second book talks about a small "hush hush" British army of "volunteers" sent on a hazardous journey to the Caucasus with the ultimate aim of capturing Baku for its oil wealth or at least denying the Germans access. While the Germans were trying to get there, they were hindered by fighting with their Turkish allies who sought that area for pan-Turkic reasons. Ultimately this British unit known as Dunsterforce was forced to withdraw but at least denied access to the enemy. I had never heard of this campaign before so it was fascinating especially as elements of the Bolsheviks were wheeling and dealing for the oil.
3. The last part summarized how in the WWI settlement all of the major countries scrambled to control the oil in the Middle East and elsewhere. This was nothing to be proud of. It was pure and simple exploitation with the indigenous people left unable to determine their fate and instead gave control to authoritarian governments. Resentment against this treatment feeds much of the conflict and instability today.
The only negative of the book is the writing was not the smoothest and was rather dense. Also, in different chapters the authored seemed to go back and forth in chronology.