Warner Oland returning via steamship to land of ancestors to assist British secret agent with unknown mission. Charming interlude aboard ship includes Chan singing song about Princess Ming Lo Fu and confessing his age (60). [He confessed his pajama size in previous film] Although warned to not go ashore, Chan sets out to meet Sir Stanley Woodland who is murdered before revealing to Chan what he had discovered. Chan defeats attempt on his life and kidnapping by gangsters. Chan meets with American agent and discovers the mission involved opium trade: "beauty of poppy conceals sting of death." Story is weak but it facilitates development of father/son relationship between Chan and his son Lee (Key Luke) who demonstrates martial arts and skills with disguise. Gang tries again to neutralize Chan but in end, key evidence is revealed and entire gang is sent off to Government House: "spider does not spin web for single fly." Recommended for those who need to see entire series.