Dang is called back to Vietnam to take over for Master Ki as guardian of his village. The gang heads to Vietnam to try and convince Dang to come back to Finnegan for graduation. While there, Adam discovers an ancient scroll that points to the mythical fountain of youth, which if found, could make Master Ki young again, releasing Dang from his duties. But to find the fountain, Adam must go up against Echo who is trying to preserve the leaf monkey habitat.

While Adam and Derby explore a hidden, underground temple in search of the fountain of youth, Tater helps Echo learn about monkey behavior, and Ivy helps Slab prepare for his first ever cover model photo shoot. All roads lead to a confrontation with a local fancy hat factory owner, who has been keeping a secret from the villagers for generations. In the end, Adam gets the gang back to Finnegan, just in time for graduation.