The film Annihilation is loosely based on Jeff VanderMeer’s novel of the same name. Annihilation follows an all-female group that is sent on an expedition to explore an uninhabited area where mysterious things have been happening. Previous groups have explored the area, with almost no one returning.

This list contains major spoilers for both versions.

1. The Tower and the Crawler

Book: The tower is central to the book, as is its mysterious occupant and interior decorator, the Crawler. The tower and the Crawler are involved with much of the action and the first death takes place here. The Crawler’s writing on the tower walls releases spores that affect The Biologist in strange ways.

Movie: Neither exists in the film. They are replaced by other creepy places and creatures. The members find an old Southern Reach base with the remnants of something terrible that happened. The members are attacked by a gator with shark teeth and a bear with a skull-like face.

2. The Journals

Book: Everyone that has been on an expedition to Area X takes a journal. The biologist discovers a mountain of journals in the lighthouse, revealing there have been many more expeditions than previously believed. The novel itself is The Biologist’s journal.

Movie: The journals are, in a way, replaced by video diaries. Lena and her members discover a memory card. There is a horrifying video of Kane’s expedition, which convinces Lena’s members that the previous group went insane.

3. The Doppelgangers

Book: The Biologist’s husband reveals in his journal that he and other members of his expedition saw doppelgangers of themselves leave the tower. The doppelgangers posed as them in the outside world, but the actual members never leave Area X. One of The Biologist’s companions also briefly has a doppelganger.

Movie: A video reveals that Kane killed himself inside of the lighthouse. Before he died, he tells someone to find his wife. That someone is shown to be his doppelganger who later left The Shimmer, posing as Kane. Soon after this discovery, Lena accidentally helps create her own doppelganger.

4. The Hypnotism

Book: The Psychologist is also a hypnotist. She has set up triggers in the minds of the expedition members, such as a trigger to comply with her authority and a trigger to send them into a trance. The Biologist discovers this when she becomes immune to hypnotism.

Movie: Lena wakes up in a tent that she doesn’t remember setting up. She and the other members only remember entering The Shimmer. Based on their food, they have probably been inside The Shimmer for three days. The psychologist seems less bothered by this than the others and gets everyone to keep moving. Where the amnesia comes from is left ambiguous.

5. The Ending

Book: The biologist is the last member of the twelfth expedition and decides to search for an island within Area X that is mentioned by her husband in his journal. The book ends with Area X still intact with The Biologist still inside.

Movie: The biologist destroys The Shimmer and returns to Area X. She visits Kane’s doppelganger, who’s now lucid and healthy. They hug, with both of their eyes showing remnants of The Shimmer.