The year is 1846, and war is brewing between the United States and Mexico. Under the pretext of a scientific research expedition, Lt. John C. Fremont arrives in Sutter's Fort with Kit Carson, famous Indian Scout, and a few men. Also arriving in Sutter's Fort is Cat Reilly, who has been widowed on the long trip west and is now in desperate circumstances. She becomes romantically involved with a Russian count as well as in Fremont and Carson's political scheming and maneuvers. Soon, she is plunged into a political maelstrom as Fremont sets up a California Republic and later brings California into the union.