Amazon's adaption of I Know What You Did Last Summer revolves around a group of friends — led by party girl Lennon Grant — who inadvertently hits Lennon's twin Allison in a car, and leave her body in a cave so they can pretend the whole thing never happened. The twist, however, is that the person the friends believe to be Lennon is actually Allison, who is posing as her twin in order to adopt the better life and escape the consequences of the accident by aligning herself with Lennon's BFFs. Of course, when people start getting murdered, and the group starts getting videos of the crimes as well as other threats, does it become clear that someone — wait for it — knows what they did last summer.

What we don't know is who that person is. Who would have motive to torture the group for "Allison's" death? Allison was a depressed loner before she made the Lennon switch, and it's established that save for Dylan (who slept with Lennon on the night of her death) and Johnny (decapitated in the second episode) she didn't have many friends. Lennon and Allison's dad Bruce not only knows the truth about the car accident, but encouraged Allison to switch places with Lennon — so he's out. So who could it be?

One person that we haven't considered is someone who is presumed dead: Lennon and Allison's mother, who allegedly died by suicide. While we haven't yet received any proof that she's alive, it's worth noting that the group was once pretty convinced that it was Allison (aka, Lennon — it's confusing, I know) who was sending them threats and murdering their friends, until her body washed up in the ocean. After that, it seemed obvious to the friends that dead people can't kill people — which might be a way for the show to draw attention away from the fact that while Lennon/Allison is really dead, their mom may not be.