After three years of wandering, Song Siming returned to his hometown. At the hospital, he saw his wife Li Xiuzhen about to jump off a building. He rushed forward to hold her back, only to learn she was pregnant—and the child was not his. His mother urged him to keep the child. While he was investigating the truth, his father committed suicide, leaving a note claiming to have killed his wife. A paternity test revealed two shocks: he had no blood relation to his father, and he suffered from XYY syndrome. The clue pointed to Wang Mingqiang, their bodyguard. His good friend was killed and the test report was stolen, but Song Siming continued his investigation. When the truth finally came to light, it turned out Wang Mingqiang was his biological brother. Wang Guizhi had made mistakes to cover up this secret; she was later arrested and despaired into taking her own life.
