Asurrogate for the inquisitive reader, cantankerous, misanthropic Frank Cahill is the device by which Dickey provides entry into the Army Air Corps training base in Peckover.

Cahill's quest for the truth about his dead son provides the pretext for introducing each of the other characters, as well as for meditations on life, death, and love. Cahill is also important for providing an outsider's perspective, that of a blind old civilian among mostly young recruits, thereby emphasizing the theme of the elusiveness of truth.

The most important character in Alnilam, Joel Cahill, never appears in the novel. Dead before the novel begins, he is the absent text that every one of the other characters — and the reader — must attempt to decode. Joel is the figure linking everyone else and the touchstone for gauging their personalities.

Joel came among the group of rebellious cadets with a few strange...