The Secret World of Og(2006)

The Secret World of Og is a children's adventure series following four kids who discover an underground cavern beneath their playhouse while searching for their lost baby brother. Deep below, they encounter a civilization of small green people fascinated by the world above ground. The inhabitants refuse to let anyone leave the cavern, fearing outsiders might reveal their secret existence. As the children navigate this hidden realm, they must find a way to rescue their brother and escape without betraying the trust of their new friends. The series blends exploration, mystery, and heart as the young protagonists learn about friendship and difficult choices in a fantastical world hidden from view.