In Dave's (Tim Allen) heart, work is always the first priority, and his wife and children at home have to give way to his career. If it weren't for this accident, he might never realize the importance of his family. After receiving a case of animal experiment, Dave launched an investigation, but unexpectedly came into contact with a long-haired dog: the long-haired dog bit him and transmitted a strange virus to him, reshaping his genes. Now, Dave has become a long-haired dog, and the long-haired dog has become Dave. Their lives have also been exchanged with each other. No one in the family knows that the pitiful and lovely long-haired dog is their relative. Dave can only live a dog-faced life, watching the long-haired dog with zero IQ occupy the position of the head of his family. What's more worrying is that Dave, who has become a dog, finally has time to watch how his family lives, and finally realizes that the love he has given them in the past is too little. But in Dave's current situation, it seems that there is only regret.