I’ve lost count of how many times I’ve watched Arrival, but it just gets better with each viewing. The cinematography is beautiful, the sound design’s incredible, and the story is compelling. But I’d like to focus on the editing, because it pushes the film to another level.

The best way to describe the structure that editor Joe Walker (12 Years A Slave, Sicario) created is through the alien symbols in the film, which are circular with many tangents and offshoots, or circuitously tangential. Perhaps with this in mind, Louise (played by Amy Adams) narrates her doubts about beginnings and endings as she copes with losing her daughter to cancer in a dim circular hospital hallway. The montage is cut slowly with the opening strings of the score, letting each shot sink in, until her daughter jumps several years, screaming “I hate you,” making clear just how much time has passed. It quickens at the end—like Hannah’s disease. This is a nice example of using the pacing of the edits to help support the narrative and heighten emotion. After the hallway, it’s back to “real-time” editing as Louise walks to her classroom and confronts the global arrival of the aliens. No more voice-over for now, just diegetic sound. But again, the secret is that we’re actually in the past. The hallway fade-to-black is the real end. It’s the arrival of Louise’s grief—the beginning of a whole different story. And in a way, by structuring it like this, the story of meeting the aliens and confronting the challenge of understanding them becomes a surrogate for confronting and overcoming the loss of a child.

But let’s go back to the opening shot. It’s a long pan down from the ceiling that reveals a lakeside living room with two empty wine glasses on the dining table. This is one of the longer shots of the film, and it’s also a shot from the end of the film, which is why Louise’s comment on being “bound by the order of time” is interesting. We’re beginning the film, but it’s not the beginning of the story. It’s a way to relish in the freedom of film editing and storytelling, but it’s also a poignant truth about life. We’re dropped into things as they’re unfolding, and it can be hard to find where things begin and end. The beauty of film editing is the ability to shape and—to some degree—control this unfolding, which gives the editor a lot of power when it comes to emotion. While the acting performances provide the raw emotional material, the editor delivers that emotion to the audience through juxtaposition—of images, sounds and ideas. For example, an actor’s performance might be great, but if the editor chooses the wide shot instead of the close up for that big emotional beat, it’s probably going to fall flat.

Getting back to the story, Louise finds herself in a new situation: arriving at the site of an alien ship in hopes of understanding them. This is the longest shot of the film, a full 75 seconds. The ominous ship hovers in the distance as clouds flow over the mountains and the alien theme takes over the soundtrack for the first time. It sounds almost aboriginal, but there’s also clear influences from the alien voices. It contrasts the melancholy strings of the opening and closing score, and it takes on a kind of “unknown” meaning. Using dramatic shifts in the score is a common technique that editors and directors use to tie scenes throughout the film together. In the big alien ship reveal, we have a long time to gaze at the imagery while the shift in the score sinks its teeth in, setting us up for it to be invoked before important scenes later.

Speaking of which, Louise’s “visions” of the future are cut with expert precision. The first vision (or tangent) happens as Louise departs from the first productive session with the aliens. She sees a vision of a girl she doesn’t know—a girl we glimpsed during the opening montage, but could also be confused for Louise’s own childhood memories. These initial visions are easy to ignore. They’re vague, blurry, and short. But the clue lies in Louise’s reaction. She clearly gags and fights back her nausea as this vision overwhelms her. Walker deftly uses L and J cuts to blend the scenes and suggest various narrative possibilities. You might be wondering what L and J cuts are, which makes sense because it’s editor jargon. Imagine two tracks on a timeline, one for video and one for audio. Now imagine a splice through both tracks. That’s called a cut, or a hard cut. When you cut to the audio from the next shot earlier than the visual cut, it’s called a J cut (the edit looks kind of like a J in an editing timeline). An L cut is the reverse, when you cut to the next visual, but linger on the audio from the previous shot for a beat. They’re both very useful tools in an editor’s toolbox, and Walker makes the most of them to heighten the significance, confusion and mysteriousness of Louise’s visions, all the while being concise.

The second vision starts with the sound of a pen raking against paper while Louise works on the alien symbols. She’s struck by reading a book to Hannah; watching a caterpillar; making ripples in a pond. The caterpillar’s form resembles the tangents of the alien iconography, making these edits effective. This isn’t exactly a form edit, which is cutting between two visually similar forms, but the caterpillar shot is close enough to the the alien forms that it functions in a similar way. It seems as if these are memories somehow flooding back to Louise, giving her insight into the language she’s trying to learn. This scene is amplified by dropping into a silence (another powerful tool in an editor’s arsenal), and then jolted out as Hannah flips a rock over and Louise looks up as if discovering a jewel underneath. But again, the true meaning is unclear. This key scene is followed by an expository montage narrated by Ian (Jeremy Renner) that serves a few purposes: condense the passage of time, give us more info about the aliens, and reset our emotional base. From here, the tangents become more frequent. This comes to a climax when we’re thrown seamlessly into Louise’s dream. This structural and narrative play helps drive the feeling of confusion. Trying to understand something just out of reach—that thing in the fog that you just can’t make out. That word you can’t define. The alien language that Louise and Ian (and humanity) are trying to figure out to avoid destruction must be communicated through the language of film, and the editing does a great job of putting us in that position—peering into a fog, communicating with unknowns, and feeling that anxiety.

The final vision before Louise goes into the ship alone is another well-done blend of the future and present coming together. Similar to Memento, there’s an inflection point when the timelines coincide. In Arrival, it’s when Louise hears Ian say, “non zero-sum game,” and then tells Hannah the term in her vision. It’s the first indication that she can affect the future and vice versa. From then on, it’s a kind of race for her to search her future for the answers to diffuse the situation in the present. And when everything ends up okay (and the obligatory news montage floats by), the present and future merge again in a form edit: Louise and Ian embrace. In the present as survivors and potential lovers, and in the future as potential parents. It’s a bittersweet ending, knowing that the grief of Hannah’s death will come, but accepting it regardless.

But maybe there’s more to beginnings and endings than we know. Perhaps Louise knows the future could change. Maybe Hannah’s fate isn’t sealed, just like humanity’s fate wasn’t sealed until she succeeded in convincing the Chinese Prime Minister to stand down. It’s the kind of ending that encourages a second viewing. And a third. And so on.