Jeremy Solter is a teenager growing up in the late 21st century. During the school year, his family lives in Southern California--but during the summer the whole family lives and works on the frontier of the Roman Empire. Not the Roman Empire that fell centuries ago, but a Roman Empire that never fell: a parallel timeline, one of an infinity of possible worlds.For in our timeline, we now have the technology to move among these. Some are uninhabitable; some are ghastly, such as the one where Germany won World War II. But many are full of resources and raw materials that our world can use. So we send traders and businesspeople--but to keep the secret of crosstime traffic to ourselves, these traders are trained, in whole-family groups, to pass as natives.
