Twins Flo and Eddie are staying with their grandad while their mum travels for work. Nosing around in Grandad's attic, they find a villainous-looking duck frozen inside a special, temperature-controlled chamber. Eddie accidentally presses the defrost button and releases super-villain Evil Duck! It turns out that Grandad, aka Fearless Frank, is a retired superhero duck who captured his nemesis, Evil Duck, many moons ago, saving society from his sinister schemes. But now Evil Duck has escaped, and Grandad is too old to recapture him alone. So Eddie and Flo are going to have to help him track the super-villain down before he gets back to his evil ways!