It's the night of the annual Autumn Equinox Festival, when the town gathers to float paper lanterns down the river. Legend has it that after drifting out of sight, they'll soar off to the Milky Way and turn into brilliant stars. This year, Ben and his classmates are determined to find out where those lanterns really go, and they made a pact with two simple rules: No one turns for home. No one looks back.

The plan is to follow the river on their bikes for as long as it takes to learn the truth, but it isn't long before the pact is broken by all except for Ben and (much to Ben's disappointment) Nathaniel, the one kid who just doesn't seem to fit in. Together, Nathaniel and Ben will travel down a winding road full of magic, wonder, and unexpected friendship.