Linguist Louise Banks's daughter, Hannah, dies in adolescence from an incurable illness. Twelve extraterrestrial spacecraft appear at twelve locations across Earth. A U.S. Army officer, Colonel G.T. Weber, recruits Banks and physicist Ian Donnelly to find out why the aliens have come. Weber takes them to an army encampment in Montana near one of the craft. On board, Banks and Donnelly make contact with two seven-limb-ed aliens, whom they call "heptapods"; Donnelly nicknames them Abbott and Costello. Banks and Donnelly begin researching their written language of complicated circular symbols. As Banks studies the language, she starts to have visions of a child who seems to be her daughter..