Genius twins Coke and Pepsi McDonald embark on a trip to Graceland and are horrified by the reappearance of their supposedly deceased arch nemesis Dr. Herman Warsaw, who marries their aunt Judy.
On a cross-country vacation with their parents, twins Coke and Pepsi, soon to be thirteen, fend off strange assassins as they try to come to terms with their being part of a top-secret government organization known as The Genius Files.