Mary Roberts Rinehart 
Dangerous Days 

Mary Roberts Rinehart (August 12, 1876 – September 22, 1958) was an American writer, often called the American Agatha Christie, [1] although her first mystery novel was published 14 years before Christie’s first novel in 1922. Rinehart is considered the source of the phrase "The butler did it" from her novel The Door (1930), although the novel does not use the exact phrase. Rinehart is also considered to have invented the "Had-I-But-Known" school of mystery writing, with the publication of The Circular Staircase (1908).She also created a costumed super-criminal called "the Bat", cited by Bob Kane as one of the inspirations for his "Batman" Published in 1919, and set on the eve of America’s entry into World War I, this complex, multi-generational family drama focuses on an ambitious businessman, Clayton Spencer, who is increasingly estranged from his wife and rebellious son, Graham. (Excerpt from Wikipedia)