Action thriller would be my choice of description of the book and I would liken the character to a modern day Indiana Jones. This is a prequel as to one of the main characters by the author, the other (in a different series) being US marine Shane Schofield, call sign 'Scarecrow'. In both cases, I would describe each the books in each series as 'unputdownable'. However this is the only current free one available through Google Play Books. play.google.com/store/books/details?id=fwHoDAAAQBAJ
As I am posting via mobile phone, lying in hosi post surgery, I am unable to copy and paste the description. Clicking through the link should take you to an available description (fingers crossed).
For variety, and if you like dragons, there is Reilly's 'The Great Zoo of China' for a fee, which is both fascinating and unputdownable. Personally I wasn't so keen about 'Hover Car Racer', again, available for a fee but I guess it's a case of each to their own.
I find the author fascinating and inspiring too. Having written a novel and sent it to numerous book houses, no one would put his book to print. Raising the finances himself, he self-published until someone picked up a copy. The rest, as they say, is history.