Cuando la escuela de Springfield se ve amenazada con el cierre por los malos resultados en las pruebas estandarizadas, el destino de la escuela recae en un estudiante que se perdió la prueba, y que debe elevar el promedio por encima del umbral mínimo: Bart Simpson.

Bart gets in trouble on Grandparents Day at school and is forced to hang out with Skinner's mother as punishment. After spending time with various grandmas in the neighborhood, he learns the benefits of hanging out with the elderly, but eventually recognizes the dangers of taking advantage of them. Meanwhile, Peekimon Get has taken over the town of Springfield.

Homer discovers that Maggie is a whistling savant and launches her baby-celebrity career. Meanwhile, Marge impresses Fat Tony with her interior design taste, and he hires her to style his brothel.

Mientras, en el futuro, Lisa escribe su carta de solicitud de admisión para la universidad de Harvard, recuerda cumpleaños decepcionantes de su pasado que le ayudaron a convertirse en quien es.

Cuando Bart desaparece, la ciudad organiza una partida de búsqueda para encontrarle. Cuando la mayoría de la gente pierde la esperanza, el Actor Secundario Bob engaña a Millhouse para que revele dónde se esconde Bart.

Mr. Burns will build a doomsday ark after he believes that the end of the world is near when he sees an old Orson Welles show about Nostradamus. Meanwhile, Professor Frink comes up with a new way of testing everyone in Springfield after Burns wants a test to determine who should go on a spaceship with him.