Incredible But True

Alain, an insurance broker, decides to purchase a new house in suburban France with his wife, Marie. They are introduced to an estate agent named Franck Chaise, who reveals an unusual feature of the property—a tunnel in the basement.

Franck explains that the tunnel has the peculiar ability to reverse ageing by three days for anyone who enters it, while also making time fast forward by 12 hours. Excited by the potential benefits, Marie convinces Alain to secure the property.

Alain invites his boss, Gérard, and his girlfriend Jeanne over to their new home. During the visit, Marie spends most of her time inside the tunnel, which she finds herself increasingly drawn to.

During dinner, the topic of conversation takes a bizarre turn as Gérard reveals that he has had an electronic penis transplant, which he now controls with his smartphone. The dinner ends on an awkward note due to this unusual admission.

A few days later, Gérard injures his electronic penis after falling at a shooting range. As the transplant was done in Japan, he travels there for repairs, instructing Alain to inform Jeanne about his business trip.

Back in France, Jeanne, who works at a bookstore, begins making unrequited sexual advances towards Alain. This complicates Alain's feelings as he grapples with his commitment to his wife, Marie.

Skeptical about the tunnel's benefits, Alain watches as Marie takes a rotten apple inside it, which emerges looking fresh. However, when he bites into it afterward, he finds it filled with ants, causing him to question the authenticity of the tunnel's effects.

After a visit to Doctor Urgent, Alain and Marie come to the heartbreaking realization that the tunnel only reverses skin age while a person's internal age remains unchanged. This insight sparks further conflict regarding Marie's desire to stay youthful.

Marie confesses her ambition to become younger and famous as a model, which leads to tension between her and Alain. Meanwhile, Gérard contacts Alain for a favor, asking him to buy a birthday gift for Jeanne.

Alain discovers Jeanne cheating on Gérard with a bookstore employee, which adds to the growing complications in his life. This betrayal becomes a pivotal moment that affects his dealings with both women.

Gérard returns from Japan, but it is revealed that he has extended his stay due to complications with his electronic penis. Upon his return, he surprises everyone by introducing a new girlfriend, Mimi.

Through the continued use of the tunnel, Marie eventually emerges as a 19-year-old, marking a significant transformation. However, she struggles to find success in her modeling aspirations amidst her rapid aging.

In a bizarre incident, Gérard's electronic penis malfunctions and catches fire while he is driving. This unfortunate event leads to a serious car accident, further complicating his life.

Following a nervous breakdown that Marie suffers, Alain makes the difficult decision to permanently close the tunnel. The consequences of their actions begin to weigh heavily on both of them.

In a shocking and distressing turn of events, Marie is hospitalized after cutting herself, revealing that her body is infested with ants. This grotesque discovery serves as a chilling conclusion to her obsession with youth.