I didn't realize I was reading "camel club #5" until I had already started the book---then I started wondering if I was reading something that had prequel books before it. (Answer, yes)
Parts of this book I really enjoyed...I liked the Camel Club members and will probably go back & read at least #1 so I know more about these characters. I also enjoyed the MI-6 character also because I like watching a British TV show about MI-6. So that worked for me.
Overall however, I thought the book went on about 100 pages too long. I don't like "unsolvable" puzzles (the ones with about 100 pieces are about my speed: ) and this story had so many unknowns that I got a bit frustrated. "Let's solve this thing already!"