I Know What You Did Last Summer Season 1 Ending Explained: The killer revealed!

Your Next Life Could Be So Much Happier

So it all comes down to this. Six weeks have passed and finally I Know What You Did Last Summer is ready to reveal exactly what did happen last summer. And boy is it awful. Before we get to that though, let’s recap the events of the entire episode.

What happens with Dylan at the police station?

We begin with Allison bolting upright after a vivid dream of running down Lennon on purpose. She breathes heavily as question marks are raised over what really happened. Speaking to Margot, Allison plays damage control and calls out Dylan, claiming he’s spreading lies and calling out Allison still being alive.

At the police station, Dylan shows up and gives his statement Lyla. Only, this comes off the back of Bruce reporting Dylan’s behaviour asĀ  suspicious and hanging around outside Allison’s place. Now, given Lyla is currently romantically involved with Bruce, this is very clearly a conflict of interest. Lyla is obviously going to side with Bruce.

Dylan seems to know this too and becomes erratic, shooting his mouth off. Lyla questions whether he has any proof but unfortunately he doesn’t. Just before leaving though, Dylan promises that more people are going to die.

What do Margot and Dylan find out?

Over at Allison’s place, Margot uses the toilet WITH THE DOOR OPEN. Honestly, these kids are awful. Anyway, she notices the used condom in the bin and questions Allison over what may have happened with Dylan that night from the other room. Allison is nonchalant to this so Margot inevitably heads over to Dylan’s and asks him.

She believes Dylan’s story over Allison’s, handing over her laptop she wiped back at the house. Margot believes there may be evidence on there they can use against Allison to prove she’s pretending to be Lennon.

Remember the note in Alison’s drawer from before? Well, she uses this against the post-it note saying “I’ll be back” and realizes the handwriting is similar. It would appear as if it’s been written by Dylan. After an encounter with her Mum outside, Margot finds out that Allison’s mum is still alive and decides to use that as evidence to use against Allison in the near future.

Is Dylan the killer?

So Margot goes hunting for Helen alone at Clara’s, while Dylan shows up at Allison’s place. Allison confronts Dylan over the note, but he claims it was meant for Allison before he realized she was actually still alive. Dylan also talks about preparing Clara for the next life as part of a prophecy but it’s never really elaborated on.

As Dylan mentions his OCD, admitting he feels the need to check on everyone at low tide, Margot rings and tells them to head over, claiming that she was wrong about everything.

Well, as they head inside Clara’s they find Allison’s mum dead. Dylan tries to ring for help but ends up knocked out for his troubles. Margot meanwhile, is sobbing in the corner. Only…not really. She suddenly stands up and admits that she killed Allison’s mum – for Lennon. The real Lennon. Dylan isn’t the killer after all, it’s Margot!

Who is the real killer?

It turns out Margot is the killer, fully aware that Allison isn’t actually Lennon. She stabs Allison straight through the gut with a knife and watches as she falls to the ground, backing away from the murderer.

Margot actually realized Allison’s social media game was way off and she was just playing along this whole time. But why? Well, it turns out she just wanted Allison to admit the truth. She killed all her friends and boyfriend to make Allison speak the truth to prevent more killings. The killings to Lennon’s friends whom she has no real obligation to beyond keeping up pretenses. Flaky motivations much?

Anyway, Margot goes on to admit she’s madly in love with Lennon, and wanted the girl to pick her over Dylan at the party. When she didn’t, that just caused Margot to grow even more angry and jealous, setting her upon this path of murderer.

Lyla happens to be sniffing around the place and overhears a gunshot. Heading inside, she finds both Dylan and Margot in the room. She asks Allison who’s the real killer… and she points out Dylan. What?

How Does I Know What You Did Last Summer end?

Lyla has Dylan arrested and taken away. with Dylan gone, Margot wraps her hand around Allison’s oxygen mask while she’s in the ambulance and prepares to pull. Only, Margot suddenly leans in and tells Allison that she’s never been more in love and kisses her on the forehead. What an absolute fruit loop.

Anyway, the police confirm that Allison is the one who died that night on the road, thanks to Bruce switching the pictures of Lennon and Allison in their frames.

Dylan is taken into a psychiatric ward for a crime he didn’t commit while Allison and Margot end up together, living their happily ever after. Allison promises never to leave this murderer’s side.

As the episode closes out, we cut across to Riley who opens her eyes. She’s still alive! Shock, horror!

Why did Allison choose Margot over Dylan?

So, this isn’t fully explained in the series but it would appear as if Allison has made a commitment to her identity as Lennon. A lot of this season has been about Allison embracing the horrible person Lennon was and grappling with the ramifications of what happened out on the road.

Margot’s twisted reasoning over why she killed everyone doesn’t make a whole lot of sense but to Allison, keeping her around seems like the lesser of two evils.

Allison’s reasoning seems to be that she’d rather shack up with a murderer than have Dylan go free, ready to run his mouth about Allison’s true identity and finding evidence to back that up.

Now, Allison has also had a habit of being mistreated in the past, especially by Lennon, and the only interpretation here is that she’s decided to fully embrace her sister’s nasty streak and leaned into her BFF Margot, regardless of how twisted and morally ambiguous this actually is. It’s still a stupid ending but it’s at least explainable a little by the logic (or lack thereof) for these characters.

The Episode Review

What a terrible ending. Now, Amazon Studios sent out the first four episodes for critics ahead of release and it’s become increasingly clear why the second half was kept hidden from those that have written full season reviews based on those eps given (notably, we’ve held off from doing that until seeing the whole show). The ending is not only ridiculous, it also leaves a lot of plot holes and contrivances in its wake.

The motivation for Margot is pretty silly to be honest, and it undoes a lot of the interesting work done regarding her mental health and depression that was touched on across the season. Now it would appear all of this was just one big act.

The other issue stems from Allison’s choice at the end, which honestly feels like something ripped right from The Dark Pictures Anthology. For those unaware, these creepy horror games are a Choose-Your-Own-Adventure title, and Allison’s choice definitely feels like one off the more wild and nonsensical.

There are lots of question marks around this and the contrivances I could dive into, such as exactly what this cult was doing and what Dylan’s “prophecy” was, but the mini cliffhanger leaves the door open for a possible follow-up season to drop. Based on this showing though, I’d be very surprised if it’s renewed. This is a really poor ending for a disappointing remake.

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You can read our full season review of I Know What You Did Last Summer here!

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