Sean(O'Dowd)istheimaginaryfriendof10-year-oldMartinMoone,theyoungestchildofafamilylivinginasmalltowninIreland.Martinhasauniqueperspectiveonlifeaidedbyanimaginaryfriend.Hisimaginationcomesintoplaybothinhischildishdrawings,whichcomealivethroughanimation,andintheridiculousschemeshecomesupwith,againstSean'sbetterjudgement.WithSean'shelp,Martinnegotiateslifeastheyoungestinachaotic,scatter-brainedfamily.