The documentary "Mon vieux" (My old man) lifts the veil of fear to discover the complex and delicate world of Alzheimer's disease. A universe where our rationality comes up against the surrealism of an altered brain. Living in another reality also becomes the daily lot of our loved ones. With tenderness, delicacy and respect, "Mon Vieux" plunges into the life of a patient and his caregiver, a father and his son: Paul and Elie Semoun. Elie Semoun spends most of his free time with his father Paul. Elie is a caregiver like any other. The complicity and tenderness of the two men are obvious. But Elijah watches helplessly as his father loses his memory. He tries to preserve and maintain his father's social ties in order to fight against the tendency to withdraw into himself. How do you continue to communicate with someone who is losing the meaning of words, take care of him and manage your own stress?