Agatha Christie is the best selling novelist of all time. That means she has sold more books than Stephen King, for instance. Or Charles Dickens. Her career spanned more than fifty years and produced sixty-six novels plus short stories and plays.
I am reading more of Christie's novels now for several reasons. First, though I had always thought of her as an old-fashioned mystery writer who belonged to previous generations, I now see she was publishing regularly through the 1960's and until her death in 1976, well into my lifetime.
Second, she wrote several kinds of novels. She is famous for Hercule Poirot and Miss Marple, and indeed they account for about two-thirds of her novels, but among the others is her best selling book, And Then There Were None, a murder mystery with no sleuth. She also wrote one narrated in the first person by the killer (I won't say which one). So there's lots to explore.
Also, since I want to write mysteries people will want to read, I'd like to learn from the best.