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.

梅根（芭芭拉·斯坦威克 Barbara Stanwyck 饰）和未婚夫琼斯（沃尔特·康诺利 Walter Connolly 饰）即将携手步入婚姻的殿堂。琼斯是一名虔诚的基督教徒，为了传教，梅根跟随琼斯来到了中国。一场意外中，两人在误打误撞之下闯入了军事禁区，就此解释了颜将军（尼尔斯·阿斯瑟 Nils Asther 饰），三人之间结下了深厚的友谊。　　随着时间的推移，颜将军渐渐爱上了天真烂漫的梅根，两人之间的距离越来越近。颜将军在事业上受到了重创，导致了众叛亲离的下场，在这危机时刻，梅根选择不离不弃的陪伴在颜将军的身旁。可是，颜将军误以为梅根这么做是为了自己的未婚夫，这误会导致两人的感情产生了裂痕。