Typical of many stories that deal with themes of psychological trauma, Going After Cacciato contains distinct ambiguities concerning the nature and order of events that occur. The chronology is nonlinear for most of the book.
The main idea of the story is, by O'Brien's estimation, that being a soldier in Vietnam for the standard tour of duty entails constant walking; if one were to put all the walking in a straight line, one would end up in Paris, where Cacciato is going.
Paul Berlin, the main character, is a frustrated soldier. During one night while on watch duty, Paul Berlin thinks about the past and events that lead him to daydream about going to Paris. The courage it takes to chase one's dreams is a recurring theme, which is often expressed through Paul Berlin's reveries.
Cacciato, who is always portrayed as self-sufficient and happy, is pursued by Berlin and his comrades in arms. Cacciato's actions are sometimes portrayed as those of a man who is not particularly bright or gifted, but who is untroubled by the larger questions of the war itself.
In the chapter "Tunneling Toward Paris", the characters escape the endless tunnels by "falling out" just as they fell in; this allusion to Alice In Wonderland helps to reveal the story as surrealistic fiction. This surrealism also appears earlier in the novel, when Cacciato flies off a mountain.
The final pages feature the juxtaposition of two statements, by Sarkin Aung Wan and Paul Berlin, which contrast the early American view (think Emerson and Thoreau) of independence and happiness against the modern view of obligations placed on the individual to conform to society. The obligations lead to complicity in atrocities.