She and her husband emigrated to the United States in 1937, when he took an academic position at Columbia University in New York, while retaining his role in the British MI6, for foreign espionage.

[5] In the early 1930s, MacInnes had collaborated with Highet to translate German literature, which helped finance their summer travels through Europe.

[7] That year he accepted an appointment as a professor and chairman of the department of classics (Latin and Greek) at Columbia University in New York City.

It was adapted into a film in 1943 by MGM director Richard Thorpe, and was promoted with the tagline “It happened on a honeymoon,” a parallel between MacInnes and Highet and the Myles couple.

MacInnes's second novel, Assignment in Brittany (1942), was made required reading for Allied intelligence agents who were being sent to work with the French resistance against the Nazis.

[9] Her 1944 book, The Unconquerable, gives such an accurate portrayal of the Polish resistance that some reviewers and readers thought she was using classified information given to her by her husband.

The Venetian Affair, for example, was published in 1963, and set in Paris and Venice; it involved Soviet agents and sleeper cells, alluded to events unfolding in Algeria and Vietnam, and contained a conspiracy to assassinate Charles de Gaulle.

This is most directly related to her influence in the state of New York, seeing as her first sixteen novels (those written up to 1966) each spent time on the international best sellers’ list (according to a 1974 People Magazine article).

A review in The New York Times praised MacInnes' body of work for its "unfailing eye for vivid backgrounds, her deft control of complex story lines, and her clear-cut presentation of each important member of her casts.

[11] MacInnes's writing reflects an affinity for Arthur Koestler and Rebecca West, as she strongly opposed any form of tyranny and totalitarianism.