Declan Desmond, an opinionated British documentary film producer, informs the students of Springfield Elementary School that he is filming a documentary in the school on the students' lives. At one point, while Declan interviews him, Bart gets hit by a ball of dirt, and he breaks down in tears. Later, Declan belittles Lisa as she goes on about the multiplicity of her interests, insinuating that she could neither be happy nor successful juggling too many hobbies or passions. Even though she is hurt by his criticism, Lisa aims to correct it and resolves to find a singular passion to which she can devote herself, astronomy. She convinces Homer to buy her a telescope, but discovers that light pollution from the city is blocking her view of the sky. After a discussion with Professor Frink, Lisa starts a petition to reduce the city’s light pollution. After gaining enough signatures, Mayor Quimby agrees to turn off the streetlights, leading to a clear view of the stars, at which many people from Springfield marvel.
Meanwhile, Bart is looking for a way to regain his popularity after being humiliated. After seeing Nelson parading around with stolen car hood ornaments, he decides to steal one off Fat Tony's car. Milhouse and Bart are foiled on their first attempt because Quimby has bowed to public pressure to switch the lights back on permanently due to rising crime. Yet the light level is set too high which means that no one can sleep so Lisa, still wanting to see the light pollution reduced, and Bart, still wanting to steal Fat Tony's hood ornament, take a now sleep-deprived Homer to the power plant and overload the generators causing a power outage, which ends the light pollution and dismays the citizens. However, Lisa points out a meteor shower and the town looks on in wonderment while Bart sneaks off and steals Fat Tony's hood ornament.
The show ends with a montage of clips from Declan's documentary.