A mother and son believe they will make publishing history when both launch books on the same day.
Joan Brady's first thriller will be published on 4 April
British-based US novelist Joan Brady's thriller, Bleedout, and son Alexander Masters' first book, Stuart - A Life Backwards, will go on sale on 4 April.
The books have separate publishers and Ms Brady said the joint publication date was a "pure coincidence".
Ms Brady was born in San Francisco but lives in Oxford, while Cambridge-based Mr Masters grew up in Totnes in Devon.
Ms Brady, 65, who won the Whitbread Prize in 1993 for her novel Theory of War, said: "It is the most extraordinary coincidence and something both publishers say they would rather had not happened."
The widow of American writer Dexter Masters added: "I have never come across anything like it before.
"I can't imagine it has happened before. And both are firsts. It is Alexander's first book and my first thriller.
"Fortunately, the launch parties are on different days so we can go to each other's party."
Bleedout, published by Simon and Schuster, unravels the mystery behind a murder in a law firm library.
Stuart - A Life Backwards, published by Fourth Estate, is a biography of a homeless man 39-year-old journalist Masters came across on the streets of Cambridge.