Thundergate (1923)

Robert Wells is an American born in China who, unbeknownst to him, has an Oriental half-brother. Wells' uncle sends him to help Ray Williams build bridges in China. Williams is in league with Chinese reactionaries and he discredits Wells by turning him into a drug addict. Wells eventually becomes an outcast and is in a stupor when he is found by his half-brother, Kong Sue, the son of the Lord of Thundergate, a powerful Mandarin reactionary.