She was born Eileen Mary Challans using Renault as a pen name. It was at the young age of eight she decided that she wanted to be a writer. She went to Oxford and studied medieval history. She used her knowledge of the era as the background for her first novel but unfortunately her first try was unsuccessful and after many rejections she tossed away her first effort.
During WW I she worked as a nurse and continued to write. Finally she had a published novel in 1939 titled “Promise of Love” which was based on her nursing experiences. Her next novel “Return to Night” about a talented doctor, won her the $150,000 Metro-Goldwyn-Mayer Prize.