The Planeteers are called by Gaia to stop a new villain, Sly Sludge from polluting the Earth with another one of his trash dumping schemes. When the Planeteers confront Sludge, he tells them that he no longer dumps trash and has found the answer to the problem of waste management forever. He "demonstrates" by having a machine that shoots intense beams of light supposedly shrink the trash, but unbeknownst to the planeteers, it's all smoke and mirrors.
By observing the chloroplasts in a leaf, the students learn that plants produce their own food and do not get it from another source. The students come to the conclusion that the chloroplasts use sunlight, air, and water to create sugar, which is used as energy for the plant.