A step in an odd direction – a moment of dizziness – and archaeologist Dan Fielding was thrust through an invisible barrier found hundred years into the past. He was still in the Mexican desert – but it was the desert of the 16th century, and Mexico was in the grip of the conquistador Hernando Cortez. <P> Inevitably, Cortez captured Fielding – and learned of the rich territory north of the Rio Grande. The land that would one day become the U.S. would be his next conquest. Unless Fielding...