Poppy is a 12-year-old who lives in a world that is divided by colors. She lives in the Blue region, where the most important things are efficiency and rules. Growing up, she was always told to not cross the border and leave Blue territory as it is highly illegal. She was taught that the neighboring orange territory was full of poor, uneducated, and unhappy people. One day, she is in the woods picking berries when a bear starts chasing her. In her panic, she runs without paying attention to where she is going and ends up in Orange territory. There, she meets a girl named Marigold. Marigold is nothing like she has learned about Orange People; she is kind and curious. Poppy ends up staying overnight with Marigold's family and starts to think that the Orange territory is not as bad as everyone says. However, she knows that she must sneak back into Blue territory the next morning and never reveal that she crossed the border. Otherwise, both she and her family could face dire consequences. Back in Blue territory, Poppy can't stop thinking about all the wonderful things she saw when she was with Marigold, and she starts to think that maybe a life full of just rules may not be great after all.