Frankenstein inspired by suicide of Mary Shelley’s half-sister, book reveals

New collection of author’s diary entries provides tragic insight

Frankenstein’s monster, as horror fans know, did not really spark into life with a bolt of lightning, but was born inside the mind of Mary Shelley during a dreary holiday on a ­mountainside above Geneva. The inspiration came as volcanic ash clouds unexpectedly blocked out the sun that summer of 1816 and she and& her friends, including the ­infamous, “bad boy” poets Lord Byron and Percy Bysshe Shelley, ­competed to tell scary stories.

But a new collection of the young author’s personal diary entries, out in March, provides strong evidence that, although the stay in the Alps set the grim mood of her novel, her imagination was ignited by something ­personal and much closer to home.