Nathan, played by Oscar Isaac, is the tech titan gazillionaire genius who created Blue Book (the most used search engine on the planet) when he was thirteen. His mountains of money and detailed planning have helped him build a secluded, state-of-the-art home/research facility which is revealed in long, slow, silent shots. It's cold, dark and filled with hard, sharp surfaces. It's also the perfect place for Nathan to work on his pet project - artificial intelligence.
He's ready to test his latest version, Ava (Alicia Vikander), to determine if her mind is indistinguishable from a human. So Nathan personally selects an earnest programer from the ranks of Blue Book to come engage in a series of sessions with Ava. Caleb (Domhnall Gleeson) interviews Ava in her glass cell while Nathan watches from his video surveillance control room.
It's a more complicated, mental version of Deep Blue playing Garry Kasparov for the grandmaster title. Only in this game of chess, there are three players instead of two. Nathan's doesn't think he's playing the game. He created the rules and set the game in motion, but sees himself more as the referee and spectator. When asked why Nathan did this, he simply responds with, "Wouldn't you, if you could?"
But the stakes are survival for the brilliant, seductive sentient robot and the young, smart examiner. They quickly drag Nathan into the game. The story is filled with tension and suspense, as we try to figure out who knows what, who trusts who, who is working with who, and most importantly, what's the next move.