In 1963, as a cosmology student at the University of Cambridge is making great strides and is determined to find a "simple, eloquent explanation" for the universe. His own world opens up when he falls deeply in love with an arts major, fellow student Jane Wilde (Felicity Jones). But, at 21 years of age, this healthy, active young man receives an earth-shattering diagnosis: motor neuron disease will attack his limbs and his abilities, leaving him with limited speech and movement, and will take his life within two years.

Together, he and Jane defy impossible odds, breaking new ground in medicine and science, and achieving more than they could ever have dreamed – well into the 21st Century.