Ed Cooper's a senior infant now and that means using the big boys' toilet. Ed needs 'to go' but he just can't. The big white toilet is very different to the junior infants' loo – with no lock on the door and goodness knows what hiding 'down there'! What can Ed do? He can't hold on forever. Maybe, just maybe, there's a way out – Gran's potty. Gran's potty is no ordinary potty but can it help save the day?