The magic that happens inside Hollywood's editing rooms often involves the ability to travel through time with a single cut. Fox Searchlight's Jackie and The Weinstein Co.'s Lion both use frequent flashbacks, while Fox's Hidden Figures shows the progression of time in more subtle ways, tracking a trio of female African-American mathematicians as they slowly gain the respect of their NASA peers during the 1960s space race. And then there's Denis Villeneuve's sci-fi drama Arrival, from Paramount, that plays by a unique set of rules. "The philosophy at the heart of the film is nonlinear time, and I got to crosscut a kaleidoscope of different moments from a life," says editor Joe Walker. "We were very free and fluid in our approach."

??Arrival centers on Amy Adams' linguist, recruited by the military to communicate with aliens that have landed on Earth, and the movie jumps across several vignettes from different periods in Adams' character's life. Some of the material from the lakeside portion in the beginning was scripted, but, as Walker says, "the vast majority was free of narrative and could fit anywhere. So a highly sensory shot of a horse — distorted by focus — served as one of the first visions experienced by Amy's character. It felt right to play it in the moments after close contact with the aliens. Gradually adding sound and increasing the frequency of these memories helped shape her experience — is she stymied by grief or suffering from contamination?"

For Lion, director Garth Davis wanted the story to be told chronologically, but he also used flashbacks to show the journey of Saroo (Dev Patel) losing his family as a child to searching for them as a young adult. "The first third of the movie covers Saroo getting lost [in a train station] and his arrival in Tasmania," says editor Alexandre de Franceschi. "The other two thirds deal with the present time. Jumping 20 years was easy; we just faded to black and put a graphic on the screen. What was more challenging was keeping the past alive during the second half, and for that we used flashbacks. They moved around quite a bit during the editing process. We wanted to convey the idea that not only was Saroo looking for his mother, but she was looking for him as well."

Editor Sebastian Sepulveda describes the editing of Pablo Larrain's Jackie as a "memory trauma puzzle" that Jacqueline Kennedy experiences in the days after the JFK assassination. "We edited the film based on fragments, scraps of memories; [it was] elliptical, guided by this emotional thread, finding interesting plot points to create a coherent narrative structure," he says. "The idea was to build bridges between the scenes only guided by this emotional path."

While Sepulveda started with Noah Oppenheim's script, which had a back-and-forth structure, scenes of a television tour of the White House and Jackie's conversations with a priest made it more complex because "we had to deal with four different layers of time."

For Theodore Melfi's Hidden Figures, editor Peter Teschner had to balance four stories: those of the three women at the heart of the film and that of NASA. As the film progresses, the viewer sees how the relationships among the women and their supervisors, co-workers and NASA steadily change. "What Ted and I did in this regard is find the proper balance between the women's work scenes and their home lives," says Teschner. "Our main concern was balancing the stories so the audience could track what was happening with the women as well as the goal of getting a man to orbit the Earth."

This story first appeared in a December stand-alone issue of The Hollywood Reporter magazine. To receive the magazine, click here to subscribe.