It's time. It's one of the most important days of their lives. They've been preparing for months. The 350 children of Dad and Mom Fly are ready to face the world for the first time. With their backpacks filled with food, they are ready to explore. McFly follows Cassandra, a young girl fly, and McFly, a young boy fly, along with their brothers and sisters, as they journey to different parts of the world. Cassandra, a city fly, experiences country life, while McFly, a country fly, experiences city life. And throughout their travels, they connect with each other. As the young flies embark on the journey of their lives, they have many adventures along the way learning important lessons about growing up. McFly communicates the message that it doesn't matter where you live, it's the dreams in your heart that really matter.