When Wellington is given a new jacket exactly like Dad's for his birthday, he's delighted! But his delight turns to disappointment when he tries it on and it's far too big. Even worse, what if it's not that the jacket is too big, but that he's too small? Luckily, Wellington's dad has a plan, and on an exciting day out that includes a ride on the bus, a super-size strawberry sundae, a toot on a tuba, and a visit to his granddad, Wellington learns that he's growing up exactly as fast as he should be--and just like his dad.