20. "Miss Jane Marple was sitting by her window. The window looked over her garden, once a source of pride to her. That was no longer so." The title of this novel comes from the poem "The Lady of Shalott" by Alfred, Lord Tennyson.
From Quiz Agatha Christie's Opening Lines 2
Answer:
The Mirror Crack'd from Side to Side
According to a number of websites, part of this novel's plot parallels an incident in the life of the actress, Gene Tierney, who contracted rubella (German measles) during her pregnancy in 1943 and as a result gave birth to a daughter who was intellectually and physically handicapped. Gene Tierney did not know how she contracted rubella until years later, when she met a female fan who told her that, during the World War II, she was a Marine. Even though she was under quarantine for rubella, she had sneaked out in order to meet the actress. There is no firm evidence that Agatha Christie actually knew about this particular incident or that she based the novel on it.