I admit it, I skipped book three and read book four. Why? Well because I couldn't get my hands on book three. Skipping books in series is never something I like doing but it does give you a great idea of how powerful a series is.
The very fact that I could instantly understand what was going on shows that the TimeRiders series is one which allows for a reader to engage no matter the book number in the series. And I just created an awful run-on sentence. But now back to the novel. This for me was a return to the original premise of the story. It featured the American Civil War and the idea that taking Abraham Lincoln out of history meant that the war kept on forever backed by British and French troops on either side. It didn't become a war about slavery but about the British and the French using American troops and the land of America. That for me was fascinating.
Technology and action wise the story again picked up and featured the elements I loved about the first novel. There was the time travel technology, there were steam-punk airships, there were genetically created creatures of various types and there were two terminator/genetically created human soldiers. And because this was in the Civil War there was heaps and heaps of shooting, fighting and blood and gore. There was even one scene where you hear about the female AI unit walking into a room and killing all 20 men inside. This would make one interesting action film.
So if you like time travel and want to pick up another series read the first novel. And then eventually you might work your way through to this one. Or perhaps you'd prefer to jump in with the fourth book and work out everything that's going on. Your move.