17-year-old Mary Katherine, or M.K., moves in with her eccentric scientist father Professor Bomba who has been searching for tiny humanoid soldiers called Leafmen. They protect the forest that Bomba lives near from wicked creatures called Boggans and their malevolent leader Mandrake. An independent young soldier named Nod decides to quit much to the ire of the no-nonsense Leafmen leader Ronin.
The queen of the forest, Queen Tara, must choose an heir to her throne and goes out to a field of leaf pods, guarded by a laid-back slug named Mub and a wannabe Leafman snail named Grub. Immediately after she chooses a pod, the Boggans attack. Tara flees the area with the pod, and though her bodyguards do their best to protect her, they are soon overwhelmed by the sheer number of Boggans. Eventually, Ronin arrives for her and the pair fly off on his hummingbird mount. They are then attacked by Mandrake and his son Dagda. Dagda is killed by Ronin, but the former shoots Tara beforehand.
Meanwhile, M.K. decides to leave after having an argument with Bomba about his research. Before she can leave, Bomba’s dog Ozzy runs into the woods. While looking for Ozzy, M.K. sees Tara falling. Dying, Tara gives her the pod and uses her magic to shrink her. She tells M.K. to take the pod to a Glowworm named Nim Galuu before she dies, and M.K. joins Ronin and the Leafmen, along with Mub and Grub. Ronin discovers that Nod has entered a race against other creatures and bugs on birds. Nod goes back on a deal with a tough bullfrog named Bufo to throw the race. Before Bufo and his two henchmen can feed Nod to a snake for not throwing the race, Ronin intervenes and orders them to leave. A reluctant Nod joins him, M.K., Mub, and Grub after hearing about Queen Tara’s death which Bufo overhears.