The canine development documentary continues by exploring how puppies use their key senses - smell, touch, sight and hearing - to absorb information about their new surroundings, and crucially, make a start on broadening their horizons. Six-week-old golden retriever Dakin demonstrates how his ever-developing brain helps improve his stature and coordination, and a litter of bull mastiff pups are left baffled by a mirror. A cocker spaniel destined to become a working dog illustrates how selective breeding can encourage desirable abilities, and a corgi with a big future as a show-dog must first overcome a few crucial hurdles.