A narrator explains that dogs are cast in movies just as human actors are. Warner Brothers needs two dogs for a segment: a smaller dog is injured, and a larger dog protects it. We go to the lot where dogs and their trainers wait to audition. We meet several, all of whom have played parts in motion pictures. All respond to visual commands, but which will be right for the parts? Two are cast and we then watch these old dogs learn new tricks, aided by positive reinforcement and a regimen that allows for only two half-hour rehearsals per day.