Margaret O'Donnel is the human name taken by an alien envoy on Earth to orchestrate a first contact. Circumstance brings her and a human named Lawrence Casey together, and plunges them into Earth's past to escape a band of mercenaries from her side of the universe sent to deliver her to her father's enemies. The time is eighteen seventy-five. The place is Wyoming. Our time travelers land in the middle of a range war between the mountain and valley ranchers. Taking sides sets in motion the future events that lead to the destruction of a third of Earth's population. Help is on the way with the knowledge that could restore Earth's timeline. There is a chance to fix it if they can avoid capture by the mercenaries or death at the hands of the valley ranchers.