In 1990, a small meteorite was sighted in the night sky by the Hubble telescope. It appeared to be on a collision course with earth, but calculations showed that it was far too small and moving far too slowly to be a threat to our home planet.
In 1997, the long-forgotten meteorite entered the atmosphere. It did not burn away, as scientists predicted; it barely even grew warm. Even so, it landed without drawing much attention on the outskirts of a village in the middle of Africa, on the edge of the Sahara.
Three months later, a safari expedition vanished while en route through the jungle. They never reached their checkpoint, within walking distance from the desert.
A research team in 1998 happened on the impact crater of the meteorite by chance. They detected high levels of radiation in the crater, though they could not identify what element had caused it. They drove to the nearby village to warn the locals of the danger, but the settlement was completely empty. Not a soul nor a body could be found for miles around. The only evidence of life left, current or past, were the long-abandoned grass huts, and a great number of footprints leading into the sands of the Sahara. None of the footprints could be matched against any living creature on record.