I Know What You Did Last Summer star Madison Iseman chats about the challenges of playing twins in Amazon Prime’s new horror series.

I Know What You Did Last Summer, Amazon Prime’s new teen horror series, is releasing the first half of its season on October 15. Based on the iconic film franchise, which was in turn inspired by Lois Duncan’s classic 1973 novel, the latest adaptation follows a group of friends whose high school graduation partying takes a deadly turn when they kill someone in a car accident. Choosing to cover up their crime rather than face the consequences, it seems the only victim is their guilty consciences. Until the next summer, that is, when a mysterious and malevolent figure reminds that of what they did and decides to ensure they pay.

While fans of either the novel or the films may not see a need for a remake, they are sure to find plenty of differences to help them enjoy the next iteration. Created by Sara Goodman (who previously worked on Preacher and Gossip Girl), the 8-episode show has an updated sensibility reflected in both its casting and its interpersonal conflicts. The expanded cast is led by Madison Iseman (Jumanji: The Next Level), who plays twin sisters Allison and Lennon. Perhaps more so than any of their friends, their lives are irrevocably changed and their family is crucially tested after the fateful accident.

Iseman spoke to Screen Rant about tackling her dual role and uncovering the dark family history that informs Allison and Lennon’s sibling rivalry.

Screen Rant: In I Know What You Did Last Summer, you obviously have a very difficult task playing two different roles. What is your approach to differentiating Allison and Lennon, yet connecting them as twins?

Madison Iseman: For me, making them both separate people was very important. Because even more than just their personalities, it’s the way they think, the way they move, and the way they process and make decisions. All those things come to play. And it was important for us that we didn’t want them to be your stereotypical twins [being] the complete opposite. I wanted them to have some similarities – they’re sisters. It was a lot of trial and error and trying to figure out what worked.

But, honestly, the most difficult part was probably just the technical side of playing twins. I’ve never done it before, but it was definitely a lot. A scene that would normally take half a day ended up taking all day.

Aside from the two girls not always getting along, their dynamic with their father is also intensely complicated because of their family history. Can you talk a little bit about how they view their father?

Madison Iseman: Their mother committed suicide when they were little girls, so there’s always been a bit of a power play of who’s going to be the woman of the house. And their father has always had a little bit of favoritism towards Lennon because she’s just always been the one who’s easier to get along with. She does great in school, she’s valedictorian; she’s always had everything come easily to her, while her sister always felt somewhat in her shadow.

I think because of that, naturally, Lennon has always had a better relationship with her father. And all of that very much comes to play in our first episode.

Have you read the original novel or just watched the films?

Madison Iseman: I’ve never read the book, but I’ve seen the movie many times. Now, it’s time. I feel like I have to go back and actually read the book.

What is it from the original films that you feel is iconic or that you would want to bring forward in this series?

Madison Iseman: It’s a fun ride. I remember seeing it for the first time, and I was just hooked. It’s just so much fun, and the characters are just so great. And it’s just storytelling at its finest – you’re in from the beginning to the end.

At least for me, that’s really what I wanted to bring here. I wanted people to be entertained from the beginning to the end, and I wanted people to be completely questioning everything along the way, which, honestly, we were too. We had no idea.

I love how the friend group seems really united even when they are falling apart. If you were a friend who was not actually involved in this situation, what advice would you give them?

Madison Iseman: Maybe get new friends. Maybe that’s the first step. I love them all, but they don’t make a great combination. That, and just ask for help. But it’s a slasher, so no one can ask for help!