'Suite Francaise'

Irène Némirovsky was a French writer of Ukrainian Jewish descent. She was 39 when she died in the infamous concentration camp, Auschwitz.

She wrote Suite Francaise in a single notebook in small handwriting, which her daughter Denise kept until 1998, unread. Only until she was going to donate it to a museum did she read the notebook and realize that it was actually a manuscript.

Technically, it's one of the earliest novels about World War II. It is set in 1940 right after the French army is unable to hold back the brunt of the German army as they made their way to Paris.

The first novella chronicles the race out of Paris to the south of France and the countryside. The second novella tells the story of a small village under German occupation and the fear of sticking up for themselves, fighting back or just biting your tongue.

The final novella is actually based on an outline, some of which apparently contradicted Némirovsky's original ideas. 

The manuscript was discovered in 1998 and published in 2004, 62 years after her death in that concentration camp due to typhus. 

Controversy has arisen as it's been discovered that her different novellas are extremely similar to existing novels about the same content. Although Némirovsky was dead before either novel was published, no one actually read her own work until 1998, after those other novels were published.