The sixth of seven brand new 39 Clues stories, leading up to one explosive reveal.

Dan Cahill loves hanging out with his new friend, Atticus Rosenbloom, a child prodigy whose genius IQ doesn't stop him from playing video games or practicing ninja moves. It's a relief to get to pretend to be a normal kid for once, and not worry about finding Clues or looking out for Vespers. But when Atticus's house is attacked by strange intruders, Dan has to rely on his Cahill training to keep them out. Are they normal burglars? Or does Atticus's family have a secret of its own?