Each of the three stories depicts three central, semi-consistent character-types: a young boy, a man, and a woman.

The novel is divided into what are essentially three discrete short stories, unified by common threads such as character names and types, story location (New York City), story themes (such as shared humanity), and the presence of Walt Whitman (whether through actual physical presence, quotation of his works via narrator or character, or the spirit of his ideas expressed through narrator or character).

The story plays with the conventions of the noir thriller as it tracks the pursuit of a terrorist band that is detonating bombs, seemingly at random, around the city.

In the story, New York City is overwhelmed with refugees from the first inhabited planet to be contacted by the people of Earth.

This concern leads Lucas to fear for the life of Catherine, Simon's bereaved girlfriend.

In this light, Lucas' fears and Whitman's transcendental poetry represent the affirmation of humanity and each individual's importance.

Scissor Sisters's "The Other Side" from the album Ta-Dah is partially based on "In the Machine", the first third of Specimen Days.