"The Road Not Taken" was published second, but is chronologically first. It depicts the arrival of the Roxolan, an ursine alien species, on Earth. The Roxolan have developed faster than light travel, and have begun building an interstellar empire. However, their technology on other fronts has not moved with the same speed. Most of their industry is comparable to Earth in the 19th Century. Typically, the Roxolan attack races that have no hyperdrive. In 2039, they encounter Earth, and, after determining that Earth has no hyperdrive, attempts conquest. They are quickly overwhelmed by the vastly superior United States military. With the Roxolan subdued, humanity gains the secret of the hyperdrive.
"Herbig-Haro", which was published first, is set 1200 years into the future, after Earth's own interstellar empire, the Terran Confederacy, has grown too quickly and collapsed. The story depicts a group of humans attempting to recover now lost technology and knowledge, and encountering a race of aliens whose own history went on a different course.