The author and journalist Peter Evans has died suddenly at the age of 78.
Evans collapsed at his home in London yesterday, his son Mark said.
The former Daily Express columnist and foreign correspondent was in the process of finishing his latest book, which is about the film star Ava Gardner, when he died.
He was also anticipating the planned film version of his 2004 book Nemesis, which was about the relationship between Aristotle Onassis, Jackie Onassis and Robert Kennedy.
Mark Evans said: "He had an amazing life. It's amazing what he's done. He had more stories to tell than anybody.
"It's just a shock. There were no signs at all."
As well as writing for the Daily Express, Evans had work published in vast numbers of other papers and magazines, including the Los Angeles Times, Vogue, The Times, The Sunday Times, and the Daily Mail.
His many books included Goodbye Baby & Amen, a 1969 collaboration with photographer David Bailey which chronicled the Swinging Sixties, and Ari, his 1986 biography of the billionaire Aristotle Onassis.
But it was his later book about Onassis - Nemesis - which was made into a West End play starring Robert Lindsay and Lydia Leonard.
The book is now the basis of a major new film which is reported to be currently in production.
It is being directed by Fernando Meirelles, the Brazilian film-maker behind the acclaimed City Of God.
Among Evans's other work was the best-selling novel The Englishman's Daughter and The Mask Behind The Mask - the first and official biography of Peter Sellers.
He leaves his widow Pamela, son Mark, daughter Lisa and two granddaughters.