Note: Stranger in a Strange Land is divided into five parts, the first of which is entitled "His Maculate Conception."
The novel begins with a history of the first expedition to Mars. Planners decide that the best combination of crewmembers for such an arduous trip would be four married couples. One unmarried man who wants to command the mission proposes to a woman with complementary skills, and with three other couples they form the crew of the spaceship Envoy. Envoy arrives on Mars but is never heard from again.
Twenty-five years later—World War III having occurred in the interim—the spaceship Champion, commanded by Captain Willem van Tromp, arrives on Mars. The Champion reports that there is native life on Mars, and one survivor of the Envoy mission.
Valentine Michael Smith, the child of two members of the Envoy crew, is brought to Earth and put in a hospital while he adjusts to Earth's atmosphere and gravity. Van Tromp explains to a meeting of the Federation High Council, the organization that now governs Earth, that although Smith is biologically human, he thinks like a Martian, whose ways are foreign to Earthlings.
In the hospital, Smith goes into deep contemplation, slowing down his bodily processes so much that the observing doctor panics, believing he may be dying. He calls in Smith's main doctor, Dr. Nelson, who explains that he has seen Smith in this condition many times before, and that it is nothing to worry about.
An orderly comes in one day and tries to get Smith to sign a contract selling the rights to his life story for a film to be entitled "I Was a Prisoner on Mars." Smith is confused, and the attempted dealing is interrupted when a doctor enters the room.
Disobeying a rule that Smith should be allowed no female visitors, a curious nurse named Gillian Boardman ("Jill") sneaks into Smith's room. Pretending she is there to perform standard nursing duties, she offers Smith a glass of water. He is uncertain, but believes that she is offering to partake in the Martian custom of "water-sharing," a spiritual rite in which two souls grow closer. Honored, he takes a sip of the water, and insists that she do the same.
Fascinated, Smith asks Jill if she is, as he suspects, a woman. He asks her questions about her gender, to which she eventually replies that she is not about to take off her clothes and show him everything. Smith is confused by her teases. He would like for her to disrobe and teach him, but he does not want to upset her and he has trouble interpreting her mood.
Newspaper columnist Ben Caxton, with whom Jill has had a longstanding flirtation, has her over to his apartment for dinner to ply her for information about Smith. Jill tells Ben about her encounter with Smith, and Ben is delighted, half-jokingly asking her to marry him. Ben tells Jill that, by various legal precedents, Smith is the legal inheritor of the fortunes of all of the Envoy crewmembers, which is a vast amount of money. Furthermore, by a legal precedent known as the Larkin Decision, Smith is technically the owner of the planet Mars.
Ben fears that the government is keeping Smith away from the press so that they can control him. The future of the administration of Secretary General Douglas, essentially the political leader of the Earth, may depend on cooperation from Smith. Ben asks Jill to plant an audio bug in the hospital to monitor Smith's room, which she does.
The bug captures a conversation between Smith and Secretary General Douglas, who insists on being alone with Smith, causing Dr. Nelson to resign his post. Douglas tries to get Smith to sign a paper releasing any legal claim he has to ownership of Mars. Again, Smith is confused, and when Douglas tries to coerce him into putting a thumbprint on the document, Smith goes into one of his death- like trances.
Having written a column baiting Douglas' administration, Ben fears that his apartment has been bugged, so he and Jill go out to dinner. They discuss the possibility that it might be politically advantageous to Douglas to have Smith dead. Jill is overwhelmed by concern for Smith.
Stranger in a Strange Land is many things at once: a science fiction epic, a tale of spiritual awakening, a bold satire, and a polemical treatment of politics, religion, and media. Robert A. Heinlein suggests the scope of the work with the title he gives Part I of the book: "His Maculate Conception." This is a reference to the Biblical concept of the Immaculate Conception, the premise that the Virgin Mary was impregnated by God without ever having had sex. The word "immaculate" means spotless, without blemish, while the extremely uncommon word "maculate" then, means spotted, blemished. By invoking the Immaculate Conception before the story even begins, Heinlein draws a parallel between Valentine Michael Smith and Jesus Christ—but whereas Christ's entry into the world was pure, Heinlein implies that Smith's conception was flawed, the product of human beings and not any deity.
The story begins at a pace so fast as to seem narrated from a God's-eye-view. Twenty-five years pass within the space of the first few pages of the novel, and World War III, an event of massive global importance, is mentioned only as an aside. From a human perspective, the omission of discussion about World War III might seem like glib and frivolous storytelling, but this humorously dry narration implies that we are instead seeing things from a vast, cosmic perspective. In Chapter III the narration shifts to a more traditional scale, where we are shown the minutiae of conversations and interactions between individuals. After establishing this cosmic perspective, Heinlein will return to it many times throughout the novel.
Heinlein's science fiction is rooted in new ways of looking at our own world, rather than speculation about the unknown. This is demonstrated by the details that are omitted when in Chapter III he telescopes from the cosmic perspective to the human details that will form most of his tale. We are shown nothing about the Champion crew's discovery of Valentine Michael Smith, we do not see how they figured out who he was or what his name was, and although there is reference to communication with a native Martian race, we are told almost nothing about them. Heinlein establishes that, though this is a science fiction novel in which a Martian race forms a pivotal part of the background of the story, this ultimately will be a story about interactions between human beings and the nature of humankind.
The third chapter also introduces the media satire that will permeate the novel, when the film executive disguised as an orderly tries to get Smith to sell his life story and call it "I Was a Prisoner on Mars." This title is evocative of similar titles of films and dime store novels in the 1950s, such as the film I Was a Teenage Werewolf, implying that the sleazy orderly-impersonator is intending to make the basest kind of exploitation film out of Smith's extraordinary and unique story. His pitch is made sillier by the fact that Smith was not a prisoner on Mars—it is just a catchy title. Though Heinlein's tone is generally a form of heightened realism, sometimes in the novel he will lapse into broad satire, particularly when it comes to mass cultural issues like the media and organized religion.
Ben Caxton's exposition regarding Smith's political importance and titanic financial worth establishes suspense. We learn that a number of powerful people would want to control Smith, and we know that Smith is neither knowledgeable enough of Earth customs nor physically strong enough to hold his own against aggressors. As the titular stranger in a strange land, Smith would seem to be entirely helpless; except that we see he is capable of things that Earth people cannot understand, such as a mastery of his own bodily processes. As for allies, in classic adventure story fashion, the only people we know that look out for Smith's interests are normal citizens. In this case, it is Caxton, the streetwise reporter, and Jill, the sexually confident young nurse.
The summary incorrectly states that Apollo is the Greek "word" for Mars. Actually, Ares is the Greek name for the god known as Mars in Latin.
Apollo is one of the few classical gods known by nearly the same name in Greek and Latin. In English, he is called Apollo in both contexts.