Dr. Phibes' latest world domination plan includes producing a massive army of nano clones. Each clone represents a different part of Phibes' personality. Shaggy and Scooby must face their toughest task yet, but little do they know that if Scooby consumes too much of the nano formula, the more likely he will become immune to its effects. Meanwhile, Robi's spring cleaning creates even more chaos for everyone.