Retired maintenance worker Zheng Guangyi spends 45 days in the hospital, and the only person who faithfully stays by his side is his widowed son-in-law, Ma Zhicheng. His biological son, Zheng Xiaojun, and daughter-in-law, Dong Yanli, rarely fulfill their filial duties. Just after the old man is discharged, they start demanding money and secretly take his property deed and bankbook, while spreading rumors everywhere that Ma Zhicheng is plotting to seize the family fortune. As Zheng Guangyi and Ma Zhicheng investigate the missing documents, they unexpectedly uncover an old factory fire case from three years earlier involving Zheng Xiuyun, Zheng Guangyi's daughter. It turns out that Zheng Xiuyun was caught in the fire while checking the factory accounts. Behind the case lies a deliberate conspiracy and the crimes of several people. After gathering evidence and going through a trial, the truth finally comes to light, and those responsible are brought to justice.