At first, Fingers refuses to believe that his Granddad has gone BARKING MAD! But what straight-thinking grownup goes around LICKING the postman, growling like a dog and chasing hospital security guards up trees? And when Fingers and his sister Sally discover a BIZARRE machine in Granddads workshop, mix-ups turn into MIND-SWAPPING madness one look at Granddads dog DaVinci is proof of that!