Lara, or GM451 as she is known by the government, is a highly trained special agent, bred by the British Secret Service for use on dangerous missions around the world. But her last mission went wrong and now she is being hunted down by an evil drugs baron, Mr Big. Lara must go undercover as a normal dog, 'choose' a family to look after her and await her retrieval by the Secret Service. But can she keep her true identity a secret? Can she thwart the plans of Mr Big? And can she bear to return to government service, after weeks of cosy domestic bliss? After an exciting struggle, Mr. Big is captured and Lara finds a way to stay with her family. But her spying days aren't over completely...