When Pepe sees an ancient commercial for a probiotic drink called ‘Gooforit’ he becomes obsessed with trying it. He finally tracks down a case, and against everyone else’s advice (it has an expiry date that pre-dates his own birth) he guzzles a bottle. Pepe’s body is instantly under attack from the bacteria contained in the rancid drink and he goes into catatonic shock. It’s up to Grandma and her shrinking potion to take the gang on a fantastic voyage inside Pepe’s body, to fight the growing enemy fungus and bring Pepe back to the land of the living.