"The Return of Martin Guerre" is a reconstruction of the famous case of Martin Guerre's return to the small town of Artigat in Southern France after being absent for eight years or so. However, "Martin" is actually an impostor named Arnaud du Tilh. He is accepted by his wife, family and friends for more than three years, during which time Bertrande becomes pregnant twice. After the so-called Martin Guerre has a dispute over family finances and the sale of some lands that the family owns, he is accused by his uncle and father-in-law Pierre Guerre of being an impostor. There are two trials, the first in the regional city of Rieux. Here Martin/Arnaud is ruled an impostor and condemned to death. "Martin Guerre" appeals the case to the regional Parliament of Toulouse. He is close to being acquitted, when the real Martin Guerre, with a wooden leg, shows up.

The main sources of the story of this famous case are from two primary sources. These are a book by Judge Jean de Coras "Arreste Memorable" and one by a lawyer, Guillaume La Sueur called "the Admirable History of the Pseudo-Martin." The author uses other secondary sources to figure out the village social structure and political structure of the time. Much of the text discusses the economic and farming conditions of families such as the Guerres and the general lifestyle of the area in the 1500s. Martin Guerre's father moves the family to the village of Artigat from the Basque country farther south near the Pyrenees Mountains and Spain, when Martin in an infant. Martin grows up and marries Bertrande de Rols when he is only fourteen years old. Bertrande is possibly as young as ten, though she is believed to be past puberty. There is a sexual problem in the marriage, Martin's impotence, but after getting some help to "take away an evil spell" from a mysterious old woman, Bertrande becomes pregnant after eight years of marriage and has a son named Sanxi. Martin shortly after disappears to go to Spain and ends up in the Spanish army.

After about eight years pass, with Bertrande without a husband, Armand de Tilh comes on the scene and hears the story of the disappearance of Martin Guerre. In a nearby town, Arnaud stops on his travels home and learns enough about Martin's intimate life from two of Martin's friends to plot his impersonation. After a period of preparation he declares himself Martin Guerre, and is met and accepted by Martin's wife Bertrande, and his other relatives and friends. The "new" Martin, Armand de Tilh, also known as Pansette (the Belly), lives in peace in Artigat with Bertrande for more than three years. Their marriage bed is busy and they have two daughters, one of which survives infancy. Could Bertrande, the wife, suspect by any difference in martial relations, that this is a different man?

After arguments with his uncle Pierre Guerre, over finances, Pierre Guerre accuses Arnaud of being an impostor. Bertrande does not support this accusation, and does all she can do defend Arnaud, the impostor, but after being put under pressure, a suit is made in Bertrande's name, by Pierre Guerre, and Arnaud is put on trial in Rieux. Witnesses are found who describe him as Arnaud de Tilh; even Arnaud's uncle appears and identifies him. Others say that they are sure that the man is Martin Guerre. Bertrande, his wife plays an ambiguous role, since her honor is in question. Whether she has believed Arnaud or not, she doesn't want to be accused of adultery. Both source books that the author uses are by Protestants, and the author considers the possibilities of Protestant sympathies at work. After all, Protestants at this time attack the Catholic Church on marriage law. They legalize divorce and also are against the practice of childhood marriages. The court reporter and judge, Coras is a secret Protestant as is the other writer on the case, Guillaume Le Sueur.

The author hypothesizes that Bertrande is in a conspiracy to coordinate her stories with Martin even though she knows he is an impostor. The prisoner is declared Armand de Tilh and sentenced to death. He appeals to the Parliament in Toulouse. There he is given a more even-handed hearing by the judges and is about to be acquitted of impersonation, when the real Martin Guerre shows up, walking on a wooden leg. Armand de Tilh is then positively identified as an imposter and sentenced to death.