After a tough year, Lucy, Freddy, and Herb Peach are ready for vacation. Lucy wants to read all of the books on the summer reading list. Freddy wants to work on his art projects (when he isn't stuck in summer school). Herb wants to swim every day. Then their dad makes a big announcement: one of the inventions their mom came up with before she passed away has sold, and now they're millionaires! But Dad has bigger plans than blowing the cash on fun stuff or investing it. He's bought a used food truck. The Peaches are going to spend the summer traveling the country selling pies. It will be the Great Peach Experiment--a summer of bonding while living out one of Mom's dreams. Summer plans, sunk. And there's one more issue Dad's neglected: none of them knows how to bake...

The "o" in "lemons" in the title is in the shape of a lemon.