The latest assignment for respected detective Charlie Chan has come directly from the government and involves the disappearance of a scientist named Harper, who was working on an extremely important serum. When the scientist is killed, Chan must sort through all very likely suspects, including the man's sister and his butler.

After the war, Matt Gordon returns to Singapore to retrieve a fortune in smuggled pearls. Arrived, he reminisces in flashback about his prewar fiancée, alluring Linda, and her disappearance during the Japanese attack. But now Linda resurfaces...with amnesia and married to rich planter Van Leyden. Meanwhile, sinister fence Mauribus schemes to get Matt's pearls.

Shanghai, China. The last expatriate Westerners still living in the city are imprisoned in a hotel by the communist authorities in order to find the spy hiding among them.