An alien botanist stranded on Earth is found by 10-year-old Elliot (Henry Thomas),who,along with his older brother Michael (Robert MacNaughton) and his younger sister Gertie (Drew Barrymore),teach him to communicate and help him build a device to contact his people to bring him home.When ET becomes sick,a medical facility is set up in Elliot's home as scientists try to study ET.The scientists find remarkable evidence indicating linked brain activity between Elliot and ET.
ET,who had previously been sick after trying to contact his species outside and catching pneumonia (or some pneumonia-like illness),miraculously recovers.Elliot helps him escape the government facility where he is being kept,and the two finally reach the aliens,who have returned after receiving ET's message.Elliot knows he must stay on Earth and cannot go with ET.