Haunted by the memory of Walter Holderlin, a soldier he killed during World War I, French musician Paul Renard (Phillips Holmes) confesses to a priest (Frank Sheridan), who grants him absolution. Using the address on a letter he found on the dead man's body, Paul then travels to Germany to find his family. As anti-French sentiment continues to permeate Germany, Dr. Holderlin (Lionel Barrymore) initially refuses to welcome Paul into his home, but changes his mind when his son's fiancée Elsa identifies him as the man who has been leaving flowers on Walter's grave. Rather than reveal the real connection between them, Paul tells the Holderlin family he was a friend of their son, who attended the same musical conservatory he did. Although the hostile townspeople and local gossips disapprove, the Holderlins befriend Paul, who finds himself falling in love with Elsa (Nancy Carroll). When she shows Paul her former fiancé's bedroom, he becomes distraught and tells her the truth. She convinces him not to confess to Walter's parents, who have embraced him as their second son, and Paul agrees to forego easing his conscience and stays with his adopted family. Dr. Holderlin presents Walter's violin to Paul, who plays it while Elsa accompanies him on the piano. The film's original title, The Man I Killed, was changed to The Fifth Commandment to avoid giving wrong impressions in the minds of the public about the character of the story. It ultimately was released as Broken Lullaby.
剧情就是一部片子的主线，就是这部影片的灵魂，如果一部片子没有一个好的主线，无疑这必定会是一部烂片。因为我们无法真正的去捕捉这部剧或是这部电影要传达给观众是什么，或是他想通过这部片子反映一个什么道理。
我杀的那位导演以自身的传统美学功底，对电影的写实艺术特性也有精深的理解和把握，他特别擅以生动的细节描绘人物的内心活动，并调动电影的各种艺术元素为塑造人物服务。
作为一门艺术，不仅要有优秀的故事和表演，还需要具备出色的技术表现。摄影、音效、音乐和特效等方面的表现都能够提升电影的观赏价值。技术的精湛与细腻能够帮助电影更好地传达情感和故事，增强观众的观影体验。
