"The Great God Pan" by Arthur Machen is a horror and fantasy novella published in 1894. A dangerous experiment opens a young woman's mind to see the supernatural god Pan, with devastating consequences. Years later, mysterious deaths and suicides follow the beautiful but sinister Helen Vaughan wherever she appears. As investigators piece together her dark origins and unnatural powers, they uncover a terrifying truth linking her to the ancient pagan deity and the failed experiment that began it all.