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.
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.