Around Earth, there are several unidentified flying objects that appear, and land in places around the globe. Colonel G.T. Weber is the head Army officer placed at the forefront of this investigation. Governmental officials are baffled around their central question: why have aliens come to Earth? The Army is unable to figure this out due to a inability to communicate with them. This leads to us meeting Louise Banks, a linguist whose former aid to the Army has brought them back to her.
Banks goes along with physicist Ian Donnelly, who is heavily interested in the science of their spacecraft and technologies, visit the site of a landing in Montana. The two meet two seven-limbed aliens and find that they have a complex written system of language. Banks (and coincidentally Donnelly) are put in charge of deciphering the language, which consists of circular symbols, all made to look different.
Banks soon finds out some of their vocabulary due to often communication with them and Donnelly. When the moment comes for Banks to ask the pivotal question, they tell her what she interprets as the phrase, "Offer weapon". Of course, this language could not be used smoothly throughout the globe, and China says it means "Use weapon". China and other alike nations break off their ties with other countries, and prepare for war. Banks continues to insist that the aliens mean no harm, and perhaps the "weapon" actually means "tool".
The next day, rogue soldiers place a bomb inside the spacecraft, intending to protect themselves from the aliens' "weapon". Banks and Donnelly, soon after, hastily return to the spacecraft. However, the aliens seem worried. They give them a complex note, and push them off of the craft. The craft flies back into the air as a bomb goes off.
The two continue to investigate the language, but now with more urgency. China, Russia, Pakistan, and more have told the aliens that they must leave within the day, or they will be forced off of the planet. Banks tells them not to do this, as the alien language itself is the tool that they were talking about. The language allows humans to understand the past, present, and future at the same time.
Banks and Donnelly fall in love, just before the camp they are at is about to be evacuated. The language has told Banks that they will have a daughter that may die very young, but she falls in love anyway, embracing every moment of her life and her daughter's story.
