Linguist Louise Banks's daughter Hannah dies at the age of twelve from an incurable illness. Twelve extraterrestrial spacecraft hover over disparate locations around the Earth. Affected nations send military and scientific experts to monitor and study them; in the United States, US Army Colonel Weber recruits Banks and physicist Ian Donnelly to study the craft above Montana. On board, Banks and Donnelly make contact with two cephalopod-like, seven-limbed aliens, whom they call 'heptapods'; Donnelly nicknames them Abbott and Costello. Banks and Donnelly research the complex written language of the aliens, consisting of palindrome phrases written with circular symbols, and share the results with other nations. As Banks studies the language, she starts to have flashback-like visions of her daughter.