Working on The Other Realm: Book Three of the Utgarda Trilogy, I have been researching people who have mysteriously disappeared, dutifully captured from Wikipedia.
Dorothy Harriet Camille Arnold (July 1, 1886 – disappeared December 12, 1910) was a wealthy American socialite and heiress who disappeared while walking on Fifth Avenue in New York City, in December 1910. The circumstances surrounding her disappearance have never been resolved, and her fate remains unknown.
