[Character]'s relation was murdered, but no one knows how, by whom, or why. Their body was a mess and only identified with a DNA test. [Character] inherits an envelope which contains a map/letter/photos. The envelope was sealed a hundred years ago, but the map/letter/photos appear to lead [character] on a journey which unravels the mystery of their relation's murder.
Possible plotlines: -Their relation was a scientist, trying to figure out how to time travel. -Their relation was involved in a cult. The map/letter/photos are related to a sacrificial ritual, planned a century ago but only just carried out.
When we are children we seldom think of the future. This innocence leaves us free to enjoy ourselves as few adults can. The day we fret about the future is the day we leave our childhood behind. — Patrick Rothfuss, The Name of the Wind