A group of astronauts embarks on a pioneering mission to colonize Mars, funded by visionary scientist Nathaniel Shepherd. During the journey, one of the astronauts, Sarah Elliot, discovers she is pregnant and dies while giving birth soon after their arrival on the Red Planet. Her son, Gardner, is kept a secret from the world and raised by the scientists in the Martian colony. Sixteen years later, Gardner, having lived his entire life on Mars, becomes increasingly curious about Earth, especially about his mother and his own origins. He forms an online friendship with a girl named Tulsa from Colorado and dreams of experiencing life on Earth.

Gardner manages to travel to Earth for the first time, awaiting critical medical examinations due to his body's adaptation to Martian gravity. However, he escapes from the scientists to find Tulsa. Together, they embark on a road trip across the United States to discover more about Gardner’s mother and his own background. Throughout their journey, Gardner experiences Earth's wonders but also faces life-threatening challenges due to his alien physiology. They grow closer as they confront various obstacles, searching for answers about his mother and his place in the universe.