What happens when your pet mouse won't stop growing? Billy Pitt's life is complicated enough--between juggling a paper round, fixing his bike, and staying out of trouble. But when he and his best mate Rusty uncover a strange grey box at the local tip, things go from ordinary to outrageous. Inside are two mysterious capsules, and after a slight accident, Billy's beloved pet mouse Marmaduke starts growing... and growing... and growing. Soon, the once-tiny mouse is the size of a dog--and he's still not done. As chaos erupts and reports of a "tip monster" spread, Billy must find a way to fix his mistake before his oversized pet becomes a full-blown public menace. But who can he trust with the truth? And is there any way to reverse the effect? Marmaduke is a fast-paced, laugh-out-loud middle-grade adventure about friendship, responsibility, and the accidental consequences of curiosity gone wild. Perfect for readers aged 8–10 who love funny science fiction and clever kids who think on their feet.