Lifetime’s fresh thriller is a real head-scratcher. But not in the way that you would normally expect a thriller to be. If you find it in your endless generosity to continue after the first scene itself, you will be left wondering why it is a thriller at all. Why couldn’t it be a mockumentary instead? Or better yet, even marketing it as a thriller parody would have been a way smarter approach. I find it hard to believe that the film’s garish hankering for the approval of its target audience’s Dateline fetish wasn’t a premeditated move on Danny J. Boyle’s part. And if this is precisely what My Sister’s Serial Killer Boyfriend (Sister Obsession) wanted to be, there are enough kudos to go around for the entire cast and crew for matching the criteria perfectly.

If you are to turn your brain off and follow the unironic mystery, you are promised a tense path to walk while the ever-agile and paranoid Maddie tries to save her little sister from the death grip of her new, ominous boyfriend. The looming question of the “charming” Haden’s real identity is only a thing of ambiguity if the film’s consistent lowbrow approach isn’t smoothed out with the denial of satire. It is fairly amusing how My Sister’s Serial Killer Boyfriend does manage to make you doubt your speculations every step of the way just by being radically plebeian. If you are unsure of the film’s self-awareness, you can’t possibly predict its next move.

My Sister’s Serial Killer Boyfriend Plot Summary and Movie Synopsis:

Sisters Maddie and Olivia suffered the scarring loss of their other sister Abigail when they were kids. Distracted in the playground, the two sisters didn’t notice when Abigail was picked up by a kidnapper. By the time they did notice that she is missing, the man had already gotten her in the van and driven off. Maddie especially hasn’t had a day of peace in her life since then. In touch with her general paranoia, her investigative instincts have led her to become a journalist, only to be reduced to writing ineffectual community pieces. Having her anxiety heightened in the wake of Abigail’s death anniversary, Maddie gets herself wrapped up in the mystery of the three women who were murdered in connected towns.

Pitching the investigative article idea to her boss Rachel only brings disappointment to Maddie. Rachel isn’t quite convinced by Maddie’s theory that the three victims were murdered by the same person who targets blonde women with strikingly similar features. Proceeding simultaneously with Maddie’s panic about the killer hitting their town next, Olivia’s house gets broken into by an enigmatic intruder. Olivia swiftly locks the bathroom door before he could get in. Frantic Maddie comes rushing to Olivia’s place when the man has already fled. Closing the door on Olivia’s obnoxiously greedy and mean landlord, Todd, is the only way for Maddie to relieve some of her stress. For the sake of her own peace of mind and Olivia’s protection, Maddie convinces her sister to move in with her.

That isn’t all Maddie is going to be content with. She drags Olivia to a self-defense class to make sure that she can defend herself if the need does arise. Olivia is instantly drawn to the teacher Haden who also happens to choose her for his first demonstration. Olivia being attracted to Haden doesn’t go unnoticed by Maddie’s watchful eyes. Obsessed with keeping her sister safe and cynical of any man she ever meets, Maddie repeatedly reminds her to be careful. When Haden does start dating Olivia, Maddie’s first instinct is to look him up. Not finding any digital footprints leads Olivia to seek the help of her friendly coworker Kyle. She urges Kyle to find out whatever he can about Haden and Olivia’s landlord Todd.

Being skeptical of men, in general, makes it impossible for Maddie to have a romantic relationship with one. The closest she comes to intimacy is meeting Jack twice to hook up and leave right after. She engages her entire energy into discovering more about the mysterious man her sister is dating. Breaking into the gym where he works only results in Haden finding her red-handed and telling Olivia all about it on their next date. Maddie’s increasing paranoia creates a rift between the two sisters and pushes Olivia even further away. That very night, someone tries to kill Maddie by locking her in her garage and asphyxiating her. The man made sure to set the scene up to look like Maddie had tried to commit suicide.

Realizing that charging Haden right off the bat was the wrong approach, Maddie now tries a different method. She apologizes to Olivia and invites her and Haden over for dinner. In the guise of appreciating how good the two look together, Maddie clicks their pictures and plans to run his picture through facial recognition systems. Haden, however, isn’t that easy to mess with. He destroys her phone and makes it look like an accident. Luckily for Maddie, the pictures were saved in the cloud storage. She asks Kyle to look up Haden using the pictures while she tries to keep Olivia safe.

My Sister's Serial Killer Boyfriend

With the new information he has, it doesn’t take Kyle too long to discover Haden’s real identity. But before he can pass the information on to Maddie, he is brutally murdered by Haden. Her own pair of scissors being used as the murder weapon makes Maddie look incredibly guilty to the investigators, one of whom happens to be Jack, the man that she got intimate with. Pointing the officers in Haden’s direction fails as Olivia stands in the way as a reliable alibi. Haden has by now come to the conclusion that the walls are closing in and decides to convince Olivia to go off on a short retreat with him. But not before stealing her phone to alienate her completely and killing Todd for being the only unfortunate man who Olivia talked to about their trip.

My Sister’s Serial Killer Boyfriend Movie Ending, Explained:

How does Maddie save Olivia’s life?

What works in Maddie’s favor all along is her instinct. It can easily and understandably be dismissed as PTSD. At least that is what Olivia perceived it to be, and Maddie, too, I’m certain, has questioned her own instincts in the lowest of the moments. However much she may wish that there were handbooks for effectively differentiating between paranoia and gut feeling, there aren’t any. But Maddie decides to follow her gut anyway. Wide-eyed Olivia soon sees the real face of Haden when he impulsively lashes out at her.

While it’s clearly controlling of him to drag her to the store, he doesn’t know that he is digging his own grave. Already suspicious, Olivia has no doubt about Haden’s intentions when the store manager addresses him as “David.” She sneakily writes a note in the bathroom and passes it on to the store manager before heading back out with Haden.

It truly baffles how it took Olivia this long to notice Haden’s bad side when the signs were there all along. If anything, Maddie’s overwhelming anxiety and high-handedness only made Olivia too inflexible in her justifications for Haden’s opaque demeanor.

The store manager gives Maddie a call and sets her on her way to hunt down Haden. Meanwhile, following up with Haden’s past workplaces and the other victims allows Maddie to know his real name, Michael Dunning. He murdered his wife six years ago and has been going on a killing spree since then. The demented Haden most likely targets women who resemble his wife brings them to his country hide-out, and kills them when they refuse to abide by his psychotic rules.

At least that is what he is doing with Olivia, with who he now sits at the dinner table and asks about the gender preference of their future babies. That is until Maddie breaks in, only to be tackled by Haden and locked up. Her white knight Jack also ends up getting shot by Haden. In the end, it is Olivia who finds his gun and kills him before things can escalate to the fatality of the victims. We see the happy sisters, away from the horrors of abduction and murder. Maddie has learned to give people a chance and now dates Jack. But she hasn’t stopped betting on the same instincts that saved all of their lives.

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My Sister’s Serial Killer Boyfriend (2023) Movie Links – IMDb
My Sister’s Serial Killer Boyfriend (2023) Movie Cast – Brianna Cohen, Rib Hillis, Revell Carpenter

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