Countdown Zero by Chris Rylander

From Chris Rylander, author of the breakout hit the Fourth Stall saga, comes the second book in the Codename Conspiracy series, a funny and clever mash-up of middle grade school story and spy adventure.

Ever since Carson Fender was let go by the secret agency that had enlisted his services to help foil a nefarious plot perpetrated by one of their former agents, he's been back to hanging with his friends, pulling pranks, and not having to lie to everyone about how he's spending his days. And that's for the best, isn't it?

Of course, this was all before a note showed up in his school lunch, informing him that Agent Nineteen had three days left to live, and that there might still be someone inside the Agency working against them. Carson has always been able to rely on his friends—but what happens when there's no one left to trust?