Nobody asked Kai Flynn if he wanted to be sent to America to live with an Air Force sergeant he's never met. But after his peace activist grandmother checks herself into a mental hospital, there aren't many options left for a free-spirited London boy.

Adjusting to life in a military community isn't easy for a peace-loving kid like Kai, and it's not long before he and Sergeant Flynn are butting heads. But things start to look up when the sergeant takes an interest in Kai's robot project for school.

Then one day, without explanation, the sergeant goes missing, and the FBI shows up at school, asking questions. Now it's up to Kai and his friends to uncover the truth, and to confront the sinister forces behind the sergeant's disappearance.