Du Yuanshan stood by with a copy of Shennong Pharmacopoeia in his hand, and his brothers regarded it as life. Wu angrily denounced Du Yuanshan's murder of his brother's family in order to seize the book. He threw himself at Du Yuanshan in desperation. Du Yuanshan's brother picked up a knife and cut it angrily at Wu.
Her family changed greatly when she was 2 years old. She was adopted by her adoptive father Wu and taught her medical skills. The adoptive father told her not to forget the family feud before she died. After taking revenge, she entered Du Yuanshan's house as a maid. When her goal was achieved, Du Yuanshan told her the truth and gave her travel expenses to leave Du's home. After Du Fu faced difficulties, Yu Er, out of guilt, was willing to go back to Du Fu to help him tide over the difficulties.
Du Minghai, the son of Du Yuanshan, has long had feelings for her. He believed that she really helped Du Fu, but Du Fu misunderstood her from top to bottom, but Du Yuanshan let her into Du Fu again. She showed extraordinary medical skill and management ability, and she became Du Fu's butler. Du Yuanshan entrusted her with the family business before her death. She also found her lost brother, Du Mingjiang, Du Fu's gentleman, but Du Mingjiang was blinded by desire and embarked on the road of no return.
After the outbreak of War of Resistance against Japanese Aggression, Yuer stuck to Du Fu Pharmaceutical Factory and, with the help of the New Fourth Army, provided medicinal materials for the anti-Japanese troops and made medicines for thousands of anti-Japanese soldiers.