White puppy Mao Mao sees her mother killed and her owner Su Zhi kidnapped. She wears her mother’s collar and goes to look for Su Zhi. Saved by Lu Heng, she repeatedly protects the Lu family, uncovers poisoning schemes, and helps find a doctor. Lu Heng gathers evidence to catch the criminal. Seven years later, Su Zhi is saved. Mao Mao keeps her promise and gains a permanent home.
