"Annihilation" revolves around the mysterious piece of land known as Area X, which the film calls The Shimmer. Every person who enters it faces death or returns forever altered.
After her return from a journey into the Shimmer, Lena (Natalie Portman) is under interrogation and her sole survivor status among a group of four puts her under suspicion.
The lighthouse in the opening sequence is important to Lena's experience. It is a turning point in our understanding of what has happened to everyone who returned.
Lena’s husband, Kane (Oscar Isaac), returns as a shadowy copy of his former self, gradually deteriorating in real-time. Meanwhile, his body is in the Shimmer.
Lena states that she is not sure what happened to the other women, but physicist Josie is merged into nature, geomorphologist Cass gets mauled by a mutated bear.
Paramedic Anya is also killed by the severely-refracted beast, and psychologist Dr. Ventress (Jennifer Jason Leigh) disintegrates into a strange, sentient cloud.