The Fogged Mirror — Carolyn Chambers Clark

One hour before fifteen-year-old Dave McClain started tailing the two men who'd exchanged suspicious information on a Paris street, Louie Devereux appeared and asked him to believe he was a tour guide, when Dave was convinced Louie was a spy.

None of this made the Paris police report. Many things didn't. Not his plan, especially not the fact an international leader was fingered for assassination, and that Louie and Dave had a plan to save him.

To get away with everything they did and not be caught, they had to count on the fact that Dave was only fifteen and this was his first mission. They also had to stump his parents and younger sister, who were also in Paris on vacation. This allowed Louie and Dave to trick people into thinking Dave was just a kid who stumbled into the secret of the fogged mirror. They had to keep it secret about the Eiffel Tower, the Iranians, the dog...