Principal Skinner calls all the Springfield Elementary School students down for an assembly to tell them which subjects they are failing. Lisa is surprisingly called up, and discovers to her horror that she is failing gym class. When she appeals to her teacher, they reach a compromise: Lisa can get a passing grade if she joins a sports program outside of school. She immediately attempts to join several, but fails, and her self-esteem is devastated. Later, the family goes to see Bart play hockey for his team, the Mighty Pigs, coached by Chief Wiggum. After the game, Bart, while ridiculing his sister for being poor at sports, begins shooting pieces of litter at Lisa with his hockey stick, and Apu, the coach of the Kwik-E-Mart Gougers, notices that she is a natural at hockey goal-tending and makes her goalie for his team. Although Lisa has no interest in hockey, she accepts, seeing this as the only way to maintain her academic credentials. As it turns out, she is remarkably talented, and leads her team to their best season ever.
Due to Homer's increasing pressure, a sibling rivalry develops between Bart and Lisa, and it peaks when the town learns that the Gougers will face the Mighty Pigs in their next match. The game proves to be a vicious one, but very close, with both Bart and Lisa playing their best. With four seconds left, Bart is tripped by Jimbo, giving him a penalty shot against Lisa that will decide the game. However, as they face each other, Bart and Lisa remember the good times they have had together as children before they began fighting. They each throw aside their equipment and hug, and the match ends in a tie. Marge admits she is proud of them, while a sobbing Homer declares them both losers and turns his attention to Maggie. Unsatisfied with the outcome (although Snake is visibly moved), the residents of Springfield begin rioting and tear the stadium to pieces while Bart and Lisa blissfully skate together across the rink.