Maurice Flitcroft (Rylance) is a resolute optimist, a 46-year-old crane driver and former comedy stunt diver who accidentally qualified for the 1976 British Open Championship qualifier. Having never played a round of golf in his life, he eventually shot a record low of 121 and was banned by the organizing committee. Maurice did not give up, repeatedly qualifying through a cat-and-mouse game and disguising himself under increasingly ridiculous aliases. His actions caused headaches for the authorities and made him a folk hero, the world's bravest and most popular sports underdog.