How to survive Grandpop's secret?

Jim Bridle blackmails Spirou’s Grandpopwith some ‘compromising’ photos: he swears to Little Spirou, he’ll reveal Grandpop’s secret in front of the WHOLE school if Li'l Spirou doesn’t do his every bidding. Little Spirou is thus forced to create all kinds of mischief under his orders... Virgil tries to help him get the secret envelope with the photos in it back, only it's no use... But what if Grandpop's secret wasn't so bad after all?