Aletha Kingman comes to the ski resort of Telluride to find refuge from a shadowed life. Cree Mackelwain comes to find the secret of his dead partner's involvement in the drug trade. What they find is the Threshold into another time. Colorado, 1901. Young Callie O'Connell faces a destiny of poverty and shame on the forbidden side of town. Her brother Bram faces a lifetime of danger in the gold mines and the gathering threat of bloodshed between miners and their bosses. At the Threshold they meet Aletha and Cree, astonished travelers from a time more than three-quarters of a century into the future. Now Callie and Bram must confront not only the unbearable struggles of their own world but the unimaginable doorway into ours.