Important lesson in "The Devil in the White City"

One important lesson in Devil in the White City by Erik Larson is to always be careful, especially in new surroundings.  H.H. Holmes, the alias of the serial killer in the book, lured women who were new to Chicago to work in his drugstore.  After he wooed them, he got them to take out life insurance and he offered them a place to stay in his mansion, which was really a specially designed murder house with airtight rooms where he could gas his victims.  Holmes would then arrange to have the flesh stripped off the bones and send the skeletons to medical schools who were desperate to have bodies.  It is highly unlikely that this scenario would happen today, as social media and cell phones make it possible to have constant contact with the outside world, but one should always maintain one's guard.  These women who were lured by the World's Fair in Chicago and the White City were never seen again, and to this day no one is really sure how many people Holmes killed.