Martin Moone is 11 and completely fed up with being the only boy in a family of girls. He's desperate for a decent wingman to help him navigate his idiotic life. So when best mate Padraic suggests Martin get an imaginary friend --- or "IF" for short --- he decides to give it a go.

Trying to earn money for a Game Boy, Martin Moone tries to find work as a stable boy, cowboy and homeboy before becoming Boyle’s main butcher boy. But Francie Feeley’s Fabulous Fishatorium across the road is luring all their customers away. Convinced something fishy is afoot, Martin and Sean decide to go on an undercover mission to discover the secrets of the mysterious fish factory. But can Agent M double-O N E get to the bottom of Feeley’s slippery schemes without ending up sleeping with the fishes himself?