The Simpsons are excited for a
solar eclipse over Springfield. After Homer's
camera obscura breaks, Marge gives up her own. As the family expresses delight at seeing the eclipse, Marge takes a peek, which
blinds her.
Dr. Hibbert informs the family that Marge's eyes must be covered for two weeks, and she must not be put under any stress. After a rat infestation, Homer takes
Maggie and
Santa's Little Helper to buy rat poison. On the way home the baby and the dog's bickering causes the car to fall off a bridge. Homer tries to
get them all across a lake in a small boat. He first takes Maggie across and puts her on the doorstep of a
convent, where the nuns take her in and refuse to give her back. While Homer hides the truth from Marge,
Lisa goes undercover as a nun and infiltrates the convent. When Mother Superior refuses to tell her where Maggie is, Lisa discovers that they are seeking a jewel. The first clue is to "seek God with heart and soul," which she accomplishes by playing a few measures of the
song by the same name on an organ, activating a
Rube Goldberg-type contraption. The next clue to find the "biggest man-made ring" in Springfield; after considering circular rings, she believes the biggest "ring" is in the Springfield Bell Tower. Arriving there, she meets
Comic Book Guy and
Principal Skinner, who tell her that
St. Teresa of Ávila had a deathbed vision of a jewel that would bring peace and harmony to the world. The gem will be revealed on the first full moon after a solar eclipse, which is that night. However, the bell is actually
papier-mâché, so they conclude that the answer is the RING in the
Springfield Sign. When they arrive, they are met by
Mr. Burns and
Smithers, who are also looking for the gem. Lisa finds writing on the letters of the sign, "Great crimes kill holy sage", and unscrambles a message that reads "Regally, the rock gem is Lisa". Mr. Burns takes the others back to the convent where Lisa announces that she is the gem child. However, Mother Superior tells her that the gem child is Maggie and rearranges the message into "It's really Maggie,
Sherlock". Maggie is put on a throne, creating a rainbow that brings peace over Springfield. Marge suddenly bursts in and takes Maggie back, and her eyes are healed upon seeing Maggie. On the way home she asks Homer if she was being selfish, but he says that he found a
replacement child;
Bart assumes the role of the "gem child", and the paradise turns into a living
Hell. ==Cultural references==