In a wondrously clanky universe populated solely by mechanical beings live memorable robots Rodney Copperbottom, a young genius inventor who dreams of helping robots everywhere; Cappy, a beautiful, dynamic and savvy bot with whom Rodney is instantly smitten; the nefarious corporate tyrant Ratchet who locks horns with Rodney; Bigweld, a master inventor who has lost his way; and a group of misfit bots known as the Rusties, led by Fender and Piper Pinwheeler. Fenders head, arms, and legs routinely fall off at the most inopportune moments. As Rodney fulfills Fenders ongoing need for repairs, the two become fast friends. Piper is Fenders tomboy kid sister, who surprises everyone with her determination and strength.