Because or maybe in spite of the number of books I read, it is a far too rare experience for one to grab me with an opening paragraph. But John Scalzi's debut novel and Hugo Award-nominated Old Man's War did just that. The opening? "I did two things on my seventy-fifth birthday. I visited my wife's grave. Then I joined the army."

Aside from raising the basic question of why a 75-year-old is joining the army, the paragraph quickly summarizes the major motivations that drive John Perry, the story's narrator: age and the death of his wife some eight years before.

Perry lives in a future in which humanity has not only made it to interstellar space, it has established colonies on numerous planets. But the universe is a rather dire place. Although there are plenty of intelligent extraterrestrial races, they have little or no desire to share their home planets with man. As a result, the Colonial Defense Forces (CDF) have waged a decades-long war to both protect humanity's colonies and expand man's reach to and control of other planets.

Earth is largely irrelevant and basically ignorant of the colonies and what the CDF does. In part to protect humanity's home, the heavily populated Earth is an unknown hinterland and life moves on much as always. It does, though, serve as a source for CDF soldiers. The catch is the CDF doesn't want anyone who isn't at least 75 years old. People like Perry do not know why, other than they speculate that youth is restored to enlistees. But enlistees can never return to Earth. If they survive their mandatory two years at the front, they have the option of "reupping" or settling on a colony planet.

Thus, even at the outset, Perry and other enlistees face difficult decisions. Do you simply live out your existence on Earth subject to the ailments and maladies of age? Or do you opt for what you believe to be restoration of youth, albeit with the risk your life could end violently within weeks? Do you forever leave your family, friends, and everything you have ever known with the carrot being that in two years you might be able to start over on some planet light years from Earth and of which you know absolutely nothing?