Thanks to "pure serendipity", Crook had chanced upon the largest collection of unpublished letters by the author of Frankenstein to be discovered in decades. The letters date between 1831, nine years after the death of her poet husband Percy Bysshe Shelley, and 1849, when Mary Shelley was already unwell with the brain tumour that would kill her two years later, and show a woman who was skilled in…