The series centers around two brothers, Wirt and Greg (Elijah Wood and Collin Dean respectively), who become lost in a strange forest called the Unknown. In order to find their way home, the two must travel across the forest, adrift in time, with the help of the wise, elderly Woodsman (Christopher Lloyd) and Beatrice (Melanie Lynskey), an irritable bluebird who travels with the boys in order to undo a curse that has affected her whole family.
Wirt, the elder brother, is self-absorbed and would rather keep to himself than to have to make a decision. His two passions are the clarinet and poetry, but he keeps this private out of fear of being mocked. On the other hand, Greg, the younger brother, is all about play and being carefree, much to Wirt’s chagrin and the danger of himself and others. Greg carries a frog (Jack Jones), whose name is undetermined and can communicate only through singing. Stalking the main cast is the Beast (Samuel Ramey), an ancient creature who leads lost souls astray until they give up and turn into “Edelwood trees”.