Lucky is a tiny, scruffy terrier dog and in the absence of effective leadership and training he rises to become the self-designated leader of his family. His mission is to protect and defend his territory. He regularly runs away and in his travels becomes a guard dog for the wrong house, parties with transvestites and develops an unhealthy obsession with a barmaid.

Evan and Jayne are responsible parents struggling to regain control of their little dog as he defends them from all the daily hazards in Port Talbot. Their children, Carys and Daniel are oblivious to the chaos caused by their canine companion and delight in his antics.

But when Lucky's family grow up, they are forced to make decisions that will change everything.