 U.S. narcotics agent Charles Sturgis (Victor Mature) trails international dope smuggler Frank McNally (Trevor Howard) by following his reluctant accomplice, Gina Broeger (Anita Ekberg), through the "pickup alleys" of New York, London, Lisbon, Rome, Naples and Athens. When Gina is finally arrested by Interpol, she helps Sturgis trace McNally and his $3,000,000 consignment back to New York.