Oxy, a precocious oxygen atom, captain of the Molecularium, is dispatched from the Unified Field of Atoms on an expedition to discover the secret of life on Earth. Along with her crew - MEL the uptight computer and Hydra and Hydro the bungling hydrogen twins - they have many misadventures exploring the Earth's atmosphere and the cycle of water molecules, through clouds, snowflakes and raindrops. Lost in the far reaches of outer space, Oxy and her crew are rescued by Carbón and his gang of intergalactic carbon atoms. With lots of bravado and a little luck, Carbón is able to pilot the ship back to Earth to explore nanospace in the metallic lattice of a penny, the polymer tangle of chewing gum, and finally the molecular machinery of a living cell.