By 2100, they had not, however, gone through an Industrial Revolution and many of their social institutions, in particular slavery, remain much as they were in earlier Roman times.

When the youngsters' mother becomes sick, their father takes her back to their home time for treatment, expecting to come back in a few days – but the cross-time travel equipment suffers a break in link, stranding Jeremy and Amanda in Polisso just as the Lietuvan Army crosses the border, placing Polisso under siege.

At the same time, the Roman authorities begin to grow suspicious of their trade mission and the origin of such items as watches and Swiss army knives which they offer for sale and which no artisan in the Empire can match.

Green, reviewing for Booklist, said, "Seemingly a series opener intended to introduce the concept of parallel worlds and Turtledove's take on it, the book succeeds as an homage to parallelworlds pioneer Piper and a well-told, engaging tale.

"[2] Peter Cannon, reviewing for Publishers Weekly, said, "Turtledove presents his teenaged heroes with a series of moral choices and dilemmas that will particularly resonate with younger fans.