The Pale Horse: Agatha Christie

I was Drawn to this book because I wanted to read it before watching the movie. I was surprised it was such a short book...it will be interesting to see how they make a movie out of it. People start mysteriously dying and there's speculation it's due to witch craft. First the people start losing their hair and soon die. Once the plot is uncovered it's obvious a man is killing them with chemical poisoning by replacing products they use regularly with chemically "induced" ones and getting away with it due to the witchcraft theory.