A Chinese-American woman tries to expose an illegal alien smuggling ring.
In an unidentified airplane flying over the ocean in which six aliens are huddled, alien smugglers Frank Barden and Andrew Sleete are trying to evade a government pursuit plane. They dump the screaming "evidence" into the sea. Escaping pursuit, they later approach wealthy merchant Quan Lin and demand he take some aliens off of their hands. They kill him when he refuses. Lan Ying Lin, his daughter, goes to wealthy society matron Mrs. Mary Hunt for help. She introduces her to an inspector and Kim Lee, a government agent. Unknown to all, Mrs. Hunt is the power behind the smuggling ring. Turning detective to catch her father's killers, Lan Ying Lin finds herself on a remote island where she takes a job as a dancer in a honky tonk operated by Otto Hartman, and discovers the island resort is a blind for an alien receiving station. She gets the evidence on Hartman and flees the island, disguised as a man, with agent Lee, in the hold of the smuggling vessel. They are discovered by the ship's captain who radios for a sea plane. They are loaded into the plane, piloted by Barden and Sleete and flown out to sea to be released.—Les Adams <longhorn1939@suddenlink.net>
A ruthless gang of people smugglers brings foreign nationals into the US illegally, and is prepared to drop their cargo from a plane to their deaths to avoid capture by the authorities.
The gang tries to force Mr. Lang (John Patterson), a wealthy importer of Oriental antiques, to employ aliens or risk his business being wrecked. He refuses and contacts Lloyd Burkett (Guy Bates Post) of the Immigration Bureau. Mr. Lang and his daughter Lan Ying Lin (Anna May Wong) set off to meet Burkett but are kidnapped. Mr. Lang is shot dead and their car is dumped in the harbor, but Lan Ying Lin escapes and goes to the house of wealthy society matron and family friend Mrs. Mary Hunt (Cecil Cunningham), who introduces her to Burkett and government agent Kim Lee (Philip Ahn). Burkett says that the identity of the gang's Boss is unknown, but their no. 2 is Otto Hartman (Charles Bickford). After Burkett, Kim Lee and Lan Ying Lin have left, it is revealed that Mrs. Hunt is the Boss. Her gang have removed incriminating evidence from Mr. Lang's safe, but she is worried that Lan Ying Lin may have more.
Lan Ying Lin turns detective, refusing the help of Kim Lee, and travels independently in search of Hartman to an island off the coast of Central America. She gets a job as a dancer at Hartman's Café bar, which is a front for people smuggling. She sees Hartman's business ledger, and discovers the Boss is a woman.
Meanwhile, Kim Lee gets a job on Captain Gulner's (Fred Kohler) people smuggling ship and makes contact with Lan Ying Lin at Hartman's Café. Kim Lee gets the ledger and Hartman is shot dead by one of the refugees. Lan Ying Lin disguises herself as a man and gets on board Captain Gulner's ship, with Kim Lee. She is discovered, and Gulner finds Kim Lee and the ledger. Lan Ying Lin and Kim Lee are taken onto the people smuggling plane to be dumped at sea, but they escape and swim to the shore unnoticed and come to Mrs. Hunt's house, where they are found by Jake Kelly (Frank Sully), her chauffeur. They think they are safe with Mrs. Hunt, but Kim Lee is taken away and tied up. Lan Ying Lin sees the incriminating ledger and realizes Mrs. Hunt is the Boss. Kim Lee reaches a phone and alerts Burkett. Kelly, who was not part of the people smuggling gang and is honest, frees Lan Ying Lin and Kim Lee. There is a fight, the authorities arrive, and Mrs. Hunt and her gang are arrested. Lan Ying Lin agrees to marry Kim Lee.
