To put it simply, Annihilation is a sci-fi film with an all female cast. Natalie Portman is in the lead as the grieving wife of an army man who vanished a year ago after going on a mission. Herself, a former soldier, she is now a professor of biology at Johns Hopkins. The weirdness begins when her husband shows up at her house with no memory of how he got there, only to inexplicably fall sick. As events unfold, we are told that there is a mysterious area in a certain part of the world called "The Shimmer", which is growing, but anyone sent in to collect information about it never returns. The movie is about the harrowing journey to uncover the mystery of this area as five women, including Lena, head into it. This is a sci-fi movie, and saying more would give away the plot too much.The rest of the cast is made up of Natalie Portman (Lena) ,Jennifer Jason Leigh (Dr. Ventress), Gina Rodriguez (Anya), and Tuva Novotny (Sheppard), all of whom play characters with specialized backgrounds that make them suitable for being involved in this mission, and all of them have their personal reasons to venture into this dangerous area. Portman does a brilliant job in portraying Lena's grief and regrets, and the way she carries on with a steely determination despite it all, hiding her constant vulnerability under a stoic mask.Jennifer Jason Leigh portrays Dr. Ventress with a coldness that evident from the first time she walks into the frame. That coldness and cynical determination is maintained throughout the movie. Dr. Ventress is a character who clearly doesn't have much to care for, and yet her mission is important enough to consume all other priorities. The rest of the cast feels a bit unexplored in a sense. It feels like we should have gotten to know the remaining three members of the team in a much better way that we do, but perhaps this would have been impossible without stretching out the film to unrealistic lengths. We do get hints about all the characters from which we can extrapolate, but that is something left to the viewers. The two men, Oscar Issac (Kane), and David Gyasi (Daniel) are ancillary characters. While they do play their roles effectively, it is a refreshing change to see the female characters be in the forefront in a movie that's not about shoes or weddings. The movie has been called an allegory for depression, grief, loss, and regret. It is indeed, that, but it also feels like a journey into nature, realizing that nature can be in equal parts, both peaceful and terrifying; both beautiful and grotesque. Much like the life of Lena, where she is haunted by the things she had that she lost, and the things she may yet lose, unless she risks everything to preserve them. Throughout the film, this unavoidable fact of her life keeps chasing her just as surely as the threats inside this zone. The film also plays with questions of change and identity, subtly shaking our confidence in the familiar concepts such as our knowledge of ourselves, our knowledge of our motivations and our desires and our ideals, and in the end, the concreteness of our reality.Just as a disclaimers, I should say there are parts in the movie that are beautiful, and parts that are deeply disturbing. This is not a movie children can enjoy. The ending of the film, like many sci-fi films is open to interpretation. It certainly seems like this is by design, as the whole movie is about questions. Questions about paths not taken, things left unsaid, decisions made only to be regretted, identity and constancy, and so on. Annihilation is a moving film wrapped in a beautiful sci-fi package.