In 1928, a mountaineer encounters a glowing sphere while on an expedition in the snowy mountains of India. He then finds himself awakening after a sudden loss of consciousness, with the sphere now gone and a scar on his hand. In the present day, Dr. Helen Benson (Jennifer Connelly), a Princeton professor, and other scientists are hastily assembled by the government in order to formulate a survival plan when it is feared that a large unknown object with a speed of 3x107m/s is on a crash course to the Earth, due to impact Manhattan in just over an hour. Nothing can be done about it because a vital military satellite has been disabled. However, the object is a large spherical biological spaceship, which slows down and lands gently in Central Park. A being (taking on the appearance of the man from the opening scene of the film) named Klaatu (Keanu Reeves) emerges from the sphere while accompanied by a large robot. Klaatu, a representative of a group of alien races, has come to assess whether humanity can reverse the environmental damage it has inflicted on planet Earth. In the ensuing confusion, Klaatu is shot, but survives. The large robot activates and proceeds to disrupt all electrical systems in the city of New York, including many of the defense systems that the military has mustered in a perimeter around the spaceship. However, before it can do any further damage, Klaatu orders it to shut down. While recovering from the wound, Klaatu is detained by Regina Jackson (Kathy Bates), the United States Secretary of Defense, and is barred from speaking to the United Nations. Klaatu manages to escape, and he soon finds himself eluding the authorities throughout Northern New Jersey, specifically Newark and the forested Highlands with Helen and her stepson Jacob (Jaden Smith).
Meanwhile, the presence of the sphere has caused a worldwide panic, and the military manages to capture the robot after it thwarts their attempts to destroy the sphere using unmanned aerial...