I Know What You Did Last Summer Wiki

Allison Grant is one of the main characters in the Prime Video original series, I Know What You Did Last Summer. She is portrayed by Madison Iseman.


Throughout the Series[]

Season 1[]

Allison was born on December 20th, 2004. Allison lives with her twin sister, Lennon Grant, and her father, Bruce Grant. She smokes and is the shier, less social twin sister. She has a huge crush on Dylan and flirts with him before finding out that her sister slept with him. She's devastated and furious with Lennon. They've had a rocky past as sisters and weren't the best of friends.

Allison gives Lennon her necklace telling her she might has well have "everything" and storms off. She gets in Lennon's car in her jacket and her friends jump in the car, assuming it's Lennon not Allison. Allison drives off and hits someone with her car - her sister, Lennon. The friends are horrified and hide Lennon's body in a cave, believing it's actually the body of Allison.

Allison then tells her father everything and he encourages her to keep the secret so he doesn't lose both daughters. Allison takes on Lennon's persona, friends, and life. She tries to cover up her tracks with Lennon's, writing a fake goodbye letter from her.

One year later, Allison, still pretending to be Lennon, starts to receive messages from a mystery person who "knows what she did last summer" and even hides a ram's head in her closet. Allison gathers together Lennon's friends to warn them and they try to figure out who knows what happened.


Allison is not very social and is on the shier side. She is the opposite of her social butterfly twin sister, Lennon. Allison smokes and keeps to herself mostly.

Physical Appearance[]

Allison is small and petite. She has short, wavy blonde hair.

Notes and Trivia[]



Episode Photos[]