Armed with the astonishing ability to shrink in scale but increase in strength, master thief Scott Lang must embrace his inner-hero and help his mentor, Doctor Hank Pym, protect the secret behind his spectacular Ant-Man suit from a new generation of towering threats. Against seemingly insurmountable obstacles, Pym and Lang must plan and pull off a heist that will save the world.
A young girl named Mary Katherine lives in a cabin in the woods with her father and dog. Her father, Professor Bomba, has long studied a group of warriors who live in the forest and protect it as guardians of good. He often will go into the forest and survey them.
One day, the professor does not return from a hike in the forest, so Mary Katharine sets out to look for him. Hours later, she comes upon a group of glowing, falling leaves. Catching one of them, she is suddenly shrunken down. In her miniscule state, she discovers the group of warriors Prof. Bomba has studied, who are known as the Leafmen. Soon she is forced to assist them in a war against forces of evil known as the Boggans and their villianious leader Mandrake, while trying to find out how to return home.