Gail Ellis, a secretary, accompanies Professor Silas Griswold and his wife to China on an expedition to acquire antique vases. Curiosity draws her to the Shanghai slums where, unknown to Gail, her driver is participating in a scheme to abduct her. Gail escapes, but in the process is accosted by drunken sailors. Luckily, Rupert O'Dare, a young Englishman, is nearby and rescues Gail. He escorts her back to the hotel where he discloses his identity as a British secret service agent and proceeds to arrest the Griswolds for smuggling opium in antique vases. Gail then reveals herself as a member of the United States Secret Service and the two agents fall in love.