What is the plot?

I can't provide a factual, unabridged spoiler for "Season 4, Episode 137" because the search results do not identify that episode's specific plot, and the available sources only give general season-level summaries, not a scene-by-scene synopsis for that episode.

What the sources do confirm is the season's structure: in Season 4, the series follows François, cousin of Jeanne d'Arc; Philippe Honoré de Roche Saint-Pierre, cousin of Louis XIV; and Jean and Renata Plancher, cousins of Napoléon, across the show's different historical settings. They also confirm the broad storylines for the season, including François's deepening misery after Ysabeau gives birth, Philippe's awkward religious turn to regain favor with Louis XIV, and Jean and Renata's attempts to get rich without drawing suspicion.

If you want, I can still help in one of these ways: - summarize the known Season 4 arcs from the available sources, - identify whether "Episode 137" corresponds to a different episode numbering system, - or, if you provide the episode synopsis or transcript, turn it into the detailed chronological spoiler you want.

What is the ending?

I can't reliably give the ending of "La Petite Histoire de France, season 4, episode 137" from the material provided, because the search results do not include a synopsis or scene breakdown for that specific episode. The results only describe the season's premise and character arcs, not episode 137's ending.

What I can confirm from the available sources is the season's character setup: François is drawn into deeper despair after Ysabeau's attention shifts to their child; Philippe tries a risky religious turn to regain Louis XIV's favor while Marie-Louise reacts in her own way; Jean and Renata turn to fraud while trying to hide their growing wealth; and the series follows these four historical-family storylines across different eras.

If you want, I can still help in one of two ways: - give you a concise summary of the season 4 character situations based on the available descriptions, - or, if you can share a synopsis, clip, or screenshots from episode 137, I can turn that into the short ending plus the expanded scene-by-scene narrative you asked for.

Is there a post-credit scene?

I can't verify a post-credit scene for La Petite Histoire de France, Season 4, Episode 137 from the search results you provided, because the results are about a different title, Dossier 137, not the TV episode you asked about.

The available results do show a trailer for La petite histoire de France, but they do not include any episode recap, end-credit description, or confirmation of a post-credit scene for episode 137.

If you want, I can still help in one of two ways: - check whether episode 137 exists under a different numbering or broadcast title, or - help identify whether the episode has any after-credits tag if you can share a clip, platform, or airing date.

How does François’s relationship with Ysabeau change after the birth of their child, and why does he feel so isolated?

François becomes deeply despondent after Ysabeau gives birth, because their newborn becomes the center of her attention and leaves him feeling neglected and alone. The season 4 material specifically says that even his promotion to sergeant does not win back Ysabeau's focus, which intensifies his sense of loneliness.

What role does the cantinière play in François’s storyline, and how does she affect the tension with Ysabeau?

The cantinière is portrayed as being madly in love with François and ready to confront Ysabeau to win him over. Her presence turns François's emotional isolation into a direct romantic conflict, creating a more volatile situation around his household.

Why is Philippe Honoré de Roche Saint-Pierre suddenly turning to religion in Season 4, and how does Marie-Louise react?

Philippe changes course religiously in an effort to regain the favor of his royal cousin Louis XIV, and the move is described as risky and awkward. Marie-Louise reacts with frustration and distress, because Philippe's new pious direction does not solve their problems and instead adds strain to their marriage.

What exactly are Jean and Renata Plancher trying to do in Season 4, and why do they hide their growing wealth?

Jean and Renata launch themselves into embezzlement and fraud after deciding that they can no longer rely on their cousin Napoleon I. They conceal their newfound bourgeois comfort because they are desperate to avoid suspicion about their social climb and financial success.

What does Marie-Louise do to cope with boredom at La Croutinière, and how does that affect the castle?

Marie-Louise fights her boredom by drinking at times and by throwing herself into eccentric scientific experiments. Those experiments are portrayed as dangerous enough to put the château at risk, turning her restlessness into a source of physical chaos in the household.

Is this family friendly?

This episode is probably not fully family-friendly for young children. The season 4 descriptions point to adult-oriented humor with drinking, corruption, deception, and marital conflict, so it is better suited to older teens and adults than to sensitive children.

Potentially objectionable or upsetting elements may include: - Alcohol use and drinking-related behavior. - Fraud, bribery, and abuse of trust, presented as comic plot material. - Arguments and relationship tension between spouses, including jealousy and conflict. - Despair, loneliness, and emotional distress in a character after childbirth and family changes. - Fantasy/period-comedy roughness that may include mockery, scheming, and social embarrassment.

Because the available descriptions are broad season summaries rather than a scene-by-scene content advisory, I cannot confirm specific graphic violence, sexual content, or profanity for this exact episode.