9 Times Mathieu from Under A Dark Sun almost pinned the blame on himself

Under A Dark Sun is a latest release on Netflix, and right after the debut of this French series, it turns into a worldwide streaming sensation—an instant global phenomenon. Across six episodes, the series crafts a suspense-packed mystery so full of twists that it keeps you guessing who the actual murderer is, because every character is a potential suspect. Among the entire cast of Under A Dark Sun, Mathieu seems especially shady. His behavior is anything but ordinary, and he’s clearly concealing something. If you watch it, you will also agree that Mathieu’s character raises eyebrows more than most. He has peculiar habits and a past that doesn’t quite add up. There are several scenes in the show that cast him in a suspicious light, marked by his questionable choices and careless conduct. Plenty of instances in the series suggest that he’s the culprit, thanks to his erratic behavior. Repeated red flags, his rash actions, and unstable demeanor make him one of the leading suspects in this murder mystery. Through this article, we are going to talk about nine times in Under A Dark Sun when Mathieu almost pinned the blame on himself.

Arriving after Alba finds Arnaud dying

In Under A Dark Sun, Mathieu’s unexplained and rapid arrival at the crime spot is definitely suspicious—the fact that no one saw him and he can’t account for how he showed up there so fast. It’s one of those murky scenes in Under A Dark Sun that makes viewers wonder whether he was just caught in the wrong place or if there’s a deeper layer to his story. By walking straight into the fresh crime scene, he unintentionally puts himself in the role of prime suspect.

At the end of her first day, Arnaud tells Alba to meet him the next day before work. However, when she reaches the estate the next morning, she finds him lying in a blood-soaked scene. Before she can do anything, he’s gone. She panics and rushes away. And then comes Mathieu—sweaty from his jog, completely oblivious to Alba’s recent presence. As he steps into the shed, he finds his father’s body. Though his shocking reaction is genuine, the timing is catastrophically bad in Under A Dark Sun.

Drunken jest at the restaurant

For the audience, it adds another layer to the puzzle—one more piece of the ever-growing mystery that keeps casting shadows over his character in Under A Dark Sun. Without even trying, Mathieu consistently lands in messy situations, and his poorly chosen drunken joke at the restaurant is a perfect example of things spiraling out of control.

At a restaurant with Lucie, a visibly tipsy Mathieu—caught somewhere between a laugh and a sulk—drops the bombshell that maybe he killed Arnaud, their father. The careless remark crashes into the moment like a slap; Lucie literally stiffens in shock. Though Mathieu attempts to shrug it off with a drunken laugh, the guilt shimmering behind his eyes says otherwise. This scene in Under A Dark Sun balances delicately between a grieving sibling and a person who knows far more than they reveal.

Anonymous tip about the murder weapon

This scene in Under A Dark Sun leaves you wondering whether he’s a schemer or merely a scared soul stuck in a horror show. Lucie shockingly discovers a gun hidden in a toilet tank, and when she gives it to Mathieu, instead of surrendering it, he places it in Alba’s cabin.

And to escalate the situation further, he calls the police station and gives them an anonymous tip about finding that gun. This underhanded move screams survival instinct and raises serious concerns about what Mathieu really knows regarding the murder. The way he deflects blame onto Alba underscores the depth of his entanglement and the lengths he’ll go to safeguard himself—or perhaps hide a darker secret. Regardless, Under A Dark Sun maintains a high level of suspense, with Mathieu’s secretive alert adding layers to the intriguing mystery shrouding him.

Clashing with Valentine over security

It’s a pivotal scene in Under A Dark Sun, nudging the needle of suspicion further. Mathieu’s exaggerated response and controlling tendencies regarding the property appear too extreme to be just tension—they point to a potential agenda. Following the unexplained burning of flowers, Mathieu becomes aggressive and blows up at Valentine, the one in charge of maintaining the grounds. He literally lashes out at Valentine—even though they only have an argument. He tells him who’s the boss, pushes him to the ground, and fires him.

Blaming him for negligence and overlooking questionable activity, Mathieu explodes in front of everyone, causing a scene that draws all eyes to him. When he goes all in, firing Valentine then and there, he throws suspicion around like confetti—even hinting at a possible partnership with Alba. The heated exchange is explosive, unstable, and cuts a little too close—enough to make people ask whether it’s just mourning or a hint of hidden guilt. Like the rest of Under A Dark Sun, it complicates things rather than delivering resolution.

Car’s suspicious GPS data

In Under A Dark Sun, nothing says “guilty vibes” quite like shady GPS data—and Mathieu delivers it in full. When Alba and Valentine snoop through his car’s navigation history, they stumble across something strange: a late-night trip into the forest right before Arnaud’s death.

Their investigation leads them to an abandoned basement nearby—dark, dusty, and just creepy enough to feel like a horror movie set. There, they find old surveillance equipment still running, capturing silent footage of comings and goings that no one was supposed to see. Naturally, Mathieu’s name shoots to the top of their mental suspect list.

In Under A Dark Sun, it’s one of those breadcrumb clues that turns suspicion into serious intrigue. Why was Mathieu lurking around the woods in the dead of night? What’s with the secret basement setup? And most importantly, what is he hiding?

Party chaos for Maison Oris deal

Desperate to keep the Maison Oris agreement afloat, he hosts a high-end party—featuring glowing lights, fine wine, and plenty of strained grins included. Rather than winning them over, he ends up waving a giant banner of suspicion around himself.

His grand gesture to save face quickly unravels into a full-scale public relations fiasco—drenched in champagne, riddled with chaos, and a painfully awkward speech in Under A Dark Sun.

For starters, he forgets his own son’s birthday. Then, he’s clearly using something stronger than espresso. His erratic behavior, muddled speech about Arnaud’s legacy, and wild mood swings quickly alienate the guests. Whispers spread. Eyebrows raise.

In Under A Dark Sun, this drug-fueled meltdown doesn’t just embarrass him—it paints Mathieu as unstable and desperate, two qualities that make him look a lot more suspicious. His need to prove he’s in control only emphasizes how much he’s spiraling out of it.

Sleeping with Omar’s associate

In Under A Dark Sun, Mathieu has a habit of making things worse for himself, and his fling with a Maison Oris negotiator does exactly that. During negotiations that could save the family estate, he ends up in bed with one of Omar’s sleek, sharp-eyed associates. But this isn’t just a random hookup—it gets messy fast.

After their steamy encounter, she casually asks if the secret heir situation is being settled or not. And boom, that one question in Under A Dark Sun ties Mathieu directly to a potential inheritance motive. Suddenly, it’s not just a fling—it’s a red flag with lipstick.

To make it even murkier, once she leaves, Mathieu pulls out a worn photo of Alba from his pocket. It’s a quiet moment that screams obsession, guilt, or maybe both. What exactly is he feeling—remorse, longing, or fear she’ll uncover something? In Under A Dark Sun, it’s another one of those moments where Mathieu can’t seem to get out of his own way.

Agreeing to institutionalize Beatrice

In Under A Dark Sun, nothing says “maybe I’m hiding something” like agreeing a little too quickly to lock up your own mother. When Beatrice’s behavior spirals—ranting about past sins, shadowy figures, and cryptic warnings—Lucie suggests it’s time to have her institutionalized.

And Mathieu? He barely hesitates. His swift nod of approval raises eyebrows, especially since he follows it up with a strangely tender kiss on Beatrice’s forehead, as if saying goodbye to someone who knows too much. In Under A Dark Sun, that mix of affection and urgency feels less like concern and more like damage control.

It’s a small moment, but one that adds another layer to the cloud of suspicion hanging over Mathieu. Is he genuinely worried about his mother’s health—or trying to silence the one person who might blow the lid off long-buried secrets? In Under A Dark Sun, it’s left deliberately unclear.

Admitting to Nadia’s affair

In Under A Dark Sun, the shocking twist that Mathieu is actually Alba’s father flips everything on its head—and that makes it look suspicious. When Alba finally confronts him, Mathieu doesn’t dodge. Instead, he quietly admits to a long-past affair with Nadia, revealing that he was the one who took Alba’s hairbrush to run a secret DNA test. The result is positive—Alba is his daughter.

It’s a raw, emotional confession in Under A Dark Sun, one that shows just how much pain he’s been carrying. He talks about his true feelings about Nadia, her pregnancy, and how he doesn’t know why she disappeared. That bitterness, that heartbreak—it’s all out in the open now.

And while it tugs at the heartstrings, it also raises suspicion. In Under A Dark Sun, this revelation does more than just rewrite family ties—it casts Mathieu in a whole new light. His motive for murder isn’t just inheritance; it’s deeply personal.