Doctor Henri Desprez meets with Jean-Marie in such unlikely ways. The kid works for a mountebank whom he boldly admits as unkind man. The philosopher and the child come together on the mountebank’s place where the sick man lies sick. Doctor Desprez comes to cure him. It isn’t the mountebank’s worsening health that surprises him but the kid instead.
He looks ignorant about the poor man’s health. He is very honest when he says he dislikes him. After the first meeting, the doctor runs into the child then they both converse, much to the doctor’s irritation. For him, Jean-Marie is too straight-forwarded, unafraid to attack his principles. Plus, Jean-Marie says he used to be a thief.
The story takes drastic turn when the doctor says to his wife, Anastasie, to adopt him. Despite her strong opposition, Doctor Desprez brings Jean-Marie to the house after the mountebank passes away. Jean-Marie turns out being a slow-learner and quite timid, the facts that disappoint the doctor. For Anastasie, Jean-Marie is the object of her play given his sluggish learning pace. She teases him much to her amusement. While for the doctor, Jean-Marie is his prime listener to his theories and rumbles. He prefers talking to the kid to his wife.
One day the doctor and his adopted son goes to Franchard with the intention of snatching what people say as a treasure. The doctor gets it, in forms of luxurious goods and money. He returns home with dreams of coming back to Paris with his wife dressed in fancy dress. He says he will telegraph Casimir, Anastasie’s brother, on their planned departure. Jean-Marie, on the other hand, doesn’t care much on the money. He says money can be harmful.
When they both reach home again, the doctor informs Anastasie on his overall plan. They both visualize how wonderful will their life be if they are rich. After that, they go to their deep slumber happily, knowing tomorrow will be their big day. But as they open their eyes, the pair is shocked.
The money is gone. Only the beautiful dress and some goods that are left. Somebody must have stolen the money! The doctor is very furious. Not long after that, Casimir comes. He suspects Jean-Marie who takes it all. The boy says yes after being forced by the businessman. It takes the wife to convince the kid to stay with them under one condition that they won’t bring the issue up again.
They agree. The house of the doctor and his wife falls down, literally, after years of decaying. They no longer have any roofs under their heads to keep them warm. They are homeless now. Thankfully, a good neighbor provides them a shelter, something that raises the doctor’s sense of humanity after all the years long.
Casimir visits them again. Instead of paying sympathy or the like, he calculates the value of the fallen house. The doctor can’t help it anymore, he is so angry with his brother-in-law. As they calculate, Jean-Marie is seen walking from across the street where the house stands.
It is Jean-Marie who actually takes the money then bring it back to this father and mother after they become humble, trustworthy of receiving it.