Helen MacInnes, 77, an elegant, cultivated woman who wove a sinister web of mystery and intrigue in 21 novels that established her as the grande dame of international spy fiction, died yesterday in New York, after having a stroke three weeks ago.

Her most recent novel, "Ride a Pale Horse," is a current paperback best seller. In all, her books have sold more than 23 million copies in the United States and have been translated into almost two dozen languages, including Urdu.

In novels that spanned the era from Nazi menace to the Cold War, MacInnes plunged her heroes -- ordinary people who happened to be in the wrong place at the wrong time -- into a trenchcoat world of skulduggery and dark plotting.

Four of her novels were made into movies, including "Above Suspicion," her first book, which was published in 1941. It was turned into a 1943 film starring Joan Crawford and Fred MacMurray.

Her books were intricately detailed, filled with authentic backgrounds. "I'm a research historian," she said. "I want hard facts, want to know what I'm writing about."

She was born in Glasgow, Scotland, and came to the United States in 1939 with her husband Gilbert Highet, a noted classical scholar at Columbia University before his death in 1978.

As an author she was known for a highly literate style, neatly constructed plots, and perceptive handling of political issues. One of her dedicated readers was Allen Dulles, former head of the CIA. He included a selection from "Assignment in Brittany" in his anthology: "Great Spy Stories From Fiction."

Other books include "The Snare of the Hunter," "Agent in Place" "The Venetian Affair" and "The Salzburg Connection."