Tseng Jing-hua and Berant Zhu embark on a road trip around Taiwan in their van, Erdai, to complete eight coming-of-age challenges. From stepping out of their comfort zones to swimming to a remote island, earning their keep on Matsu, and joining the Bunun tribe in a search for roots, they face physical, emotional, and moral tests. As they turn 25, they grapple with inner struggles, endurance, and values, all while seeking the elusive secret of adulthood. Will they conquer these challenges and transition into adulthood?