Anna Peters, the unorthodox New World Oil Company researcher, learns the price of the good research job she obtained after her successful adventures in The Big Payoff. The Chairman of the Board wants her to do a little favor: track down Crystal Blythe, a feckless young woman soon to inherit the lion's share of New World stock. Crystal and her twin brother Edward have been living in France, and Anna is dispatched on a working holiday to locate the missing girl.
Paris, art, culture, great food-the trip sounds terrific. Unfortunately for Anna and her artist lover Harry Radford, the young Blythes have gotten themselves into bad company, including gun runners and espionage agents from two countries. Anna learns she can't trust the charming and talented Blythes, and wonders if they can even trust each other.