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.

Once the twins get their feet back on the ground, they embark on the final leg of their trip, which will take them from the Hoover Dam all the way to the Golden Gate Bridge. Chased by nefarious villains, the twins will be trapped with a venomous snake, pushed through a deadly turbine, and thrown into a volcano. And craziest of all, their parents might finally believe them!

"Coke and Pepsi McDonald continue on their dangerous cross-county road trip, stopping at strange-but-real destinations in the South and facing such perils as an evil Elvis impersonator, a vat of acidic soda, and a giant recycling shredder"--

When a British student-teacher arrives, A. J. and his friends wonder if her all-black clothing and love of blood sausage mark her as a vampire, while Mr. Granite simply hopes her musician-boyfriend will stay away long enough for a math lesson

"It's time for the annual Ella Mentry School talent show, and this year Principal Klutz has hired a wacky professional, Mrs. Lane, to help the kids with their talents"--

Principal Klutz has invited a special guest to Ella Mentry School. Her name is Miss Aker, and she's going to show A.J. and his friends how to create cool things out of materials like balloons, straws, and even Popsicle sticks! But what happens when they make a robot so smart, it plans to rule the world? Can anyone stop it?!

Ella Mentary School is having a science fair! Guest scientist Dr. Snow has arrived to help A.J. and his friends conduct their own cool experiments. But what is "the snowman" really planning? And what does STEM even stand for anyway?

A.J. is planning a big birthday to celebrate turning 9 and his parents even hire a party planner named Mr. Marty. Mr. Marty orders some weird stuff to celebrate though.

"After noticing that A.J. and his friends' geography knowledge could use some work, Mr. Cooper invites to class just the person to help. Globetrotter Mrs. Barr speaks seven languages and has visited nearly two hundred countries! But why does she carry a suitcase everywhere she goes? And why does she open a window whenever she walks into a room? Perhaps Mrs. Barr has something to hide"--Provided by publisher.

Second-grade graduate A.J. and his family rent a beach house, but summer vacation is ruined when annoying Andrea shows up and develops a crush on the lifeguard