Diego is a friendly and curious cat. He loves to roam and visit people. On the day that his family moves to a new house, Diego cannot be found. Maria and Juan look everywhere for him but no success.

Later, when Diego returns to his now-empty home, his family is gone. What will Diego do? Who will take care of him? "Diego, The Lonely Cat" is the story of how Diego uses his courage and intelligence to find his home and family.