I Know What You Did Last Summer Ending & Killer Identity Explained
I Know What You Did Last Summer's season 1 finale had many revelations, including the identity of the killer. Here's how it could set up season 2.
Warning: This post contains spoilers for I Know What You Did Last Summer's season 1 finale.
I Know What You Did Last Summer season 1 ending and the killer’s identity explained. The Amazon series, which is a modern take on Lois Duncan’s 1973 novel of the same name, came to an interesting conclusion after eight episodes of mystery, murder, and drama.
I Know What You Did Last Summer's season 1 finale saw Alison tested in more ways than one. The arrival of her estranged mother Helen, whom Alison previously believed was dead, paralleled the pair's situations and inclinations to lie to those around them to protect themselves. With Dylan finally learning the truth about Alison and a dream sequence showing how deliberate she was when running over her twin sister Lennon, Alison found herself in an unexpectedly difficult situation that ultimately jeopardized her precarious secret-keeping and the lie she'd built around her identity.
I Know What You Did Last Summer season 1 ended with several questions answered, and several more left hanging, paving the way for a new storyline to emerge in a potential season 2. With the killer revealed and a new alliance formed, I Know What You Did Last Summer showed the true colors of Margot and Alison.
I Know What You Did Last Summer managed to keep the killer’s identity a secret until the very end of season 1, though it offered a major clue as to who it could be in episode 7 — Margot muttered that Alison (still masquerading as Lennon) had the same scar as her dead twin sister. That, more than anything that came before, suggested Margot at the very least knew the truth about Alison’s identity. However, I Know What You Did Last Summer’s season 1 finale confirmed it was Margot all along. Margot killed Helen, Alison’s mother, Johnny, Riley, and the cop who was looking a bit too closely at the case. She murdered all of these people in a bid to coax the truth out of Alison about pretending to be Lennon — Margot also wanted to frame Alison for the murders afterward.
Margot figured if she killed all of the friends who suspected something was off with Alison, the still living twin would come clean and admit her big secret to Margot. Alison sleeping with Dylan pushed Margot over the edge, however, driving a wedge between the slow-burning intimacy that was drawing them closer to each other. What’s interesting here is that Margot figured out Alison’s true identity mere months after Lennon was killed — based on how she posed in pictures posted to social media — and then plotted to kill so that Alison would confess to her. She even employs the people around her — including her mother, who framed Clara with the spiders, and Margot’s driver Kyle, who pushed her out of the window. All told, Margot’s behavior was terrifying, but there were also layers of deep-rooted possession.
Riley was stabbed by Margot in I Know What You Did Last Summer season 1’s episode 6, seemingly dying from blood loss. So it was surprising to find out Riley was still alive at the end of the season 1 finale. It’s possible the honey Clara covered her in stopped her wounds from getting worse and, rather than dying, Riley was just passed out and presumed dead. The honey coating likely did what it was supposed to do, preserving her body. What’s more, honey has antioxidants and antibacterial properties that help wounds heal, as well as pH components that encourage oxygen. The honey essentially acted as a bandage for her wounds, speeding up the process of healing after being completely wrapped in it.
Despite Margot stabbing Alison in the stomach, she blamed Dylan for the murders to protect her. Margot knew Alison’s secret and it was Dylan who Police Chief Lyla suspected was not telling the truth about Alison’s true identity. In a bid to protect herself and the secret of killing and stealing the identity of Lennon, Alison chose to put Dylan in the line of fire precisely because she knew he was all about justice and making things right. Not blaming Dylan in a charged moment would’ve been more damaging to Alison’s reputation in the long run because he would have tried to out her publicly. Accusing Dylan of murdering Riley, Johnny, and the others permanently silenced him and allowed Alison to protect herself from facing any consequences for her actions in I Know What You Did Last Summer season 1 — even if that meant letting another killer like Margot walk free. It’s all pretty twisted.
Dylan was rather unperturbed after seeing Clara dragging Riley’s body into the cave where they laid the real Lennon to rest a year prior. Clara was dismissed or accused of being the murderer throughout I Know What You Did Last Summer season 1, but Dylan connected with her on a wholly different level. Clara was found dead in the cave, her body covered in honey. Dylan revealed he set her free and that he prepared her for the prophecy and the afterlife, which the cult heavily believed in. Throughout the I Know What You Did Last Summer season 1 finale, Dylan would offer hints about his induction into the cult, though whether he was always a part of it or joined after speaking with Clara remains unclear.
However, Dylan was taken with the cult’s teachings, and in preparing the bodies for the afterlife in the hopes of redemption. Dylan seems to have found some solace in the cult, and in its bible particularly, as it discusses having no redemption in this life. Out of all the characters in I Know What You Did Last Summer, Dylan was the only one who felt any remorse about Lennon’s death and his part in it. His association with the cult might put him at ease in that he’s trying to seek redemption for his own afterlife rather than trying to do so while he’s still alive. Dylan might have gone to jail at the end of season 1, but he had the cult’s bible with him (which is assumed to have been given to him by Clara before she died) to make him feel better, preaching to the other inmates to grow the cult after losing so many of its members.
While I Know What You Did Last Summer wrapped up the mystery regarding the killer and the identity of Alison’s mother, there are still plenty of things left hanging that could be picked up in a potential season 2 (if Amazon renews the series). Dylan was confirmed to have the cult’s bible and I Know What You Did Last Summer’s season 1 finale dropped a few clues about what the cult’s members really wanted out of all this while still keeping details fairly vague. Season 2 could reveal more about how they function through Dylan and Fred, who is one of the last living members of the Wai Huna cult. Fred could return to find out what happened to Helen, which could then lead him to Dylan and the cult’s bible, which Helen was searching for following Clara’s death to keep the prophecy safe (whatever that means).
Perhaps he will also want revenge after what happened to Helen — and there’s also Bruce to contend with as well, who knows Alison’s secret and probably knows Dylan didn’t actually commit the murders. Riley confirmed to be alive in I Know What You Did Last Summer’s season 1 finale could also mean trouble for Alison and Margot in season 2. After all, she is the only other person besides Dylan who poses a threat to them. She might not have seen who stabbed her, but her return could pose a problem for the murderous duo. It’s possible she might go see Dylan in prison, who will tell her the truth and lead Riley to mess with Alison and Margot as payback for what they did and how that led to her near-death experience. The lack of resolution regarding Alison’s secret, as well as being partners with Margot and the threat of being revealed hanging over her, also leaves a lot for I Know What You Did Last Summer season 2 to potentially explore.