After Great Aunt Gladys dies, the Simpsons attend the funeral and subsequent reading of the will. On the video will, Great Aunt Gladys warns Patty and Selma not to die alone without a husband and children as she did. Selma starts to worry that her biological clock may be ticking, and decides to find a way to become pregnant. Selma tries video dating and eventually considers an anonymous sperm donor.
Meanwhile, Homer promises Bart and Lisa that they will go to Duff Gardens, a popular amusement park, but Homer becomes ill after eating a spoiled sandwich. Marge, in an effort to give Selma a chance to experience the responsibilities of parenthood, nominates her to take the two. Bart and Lisa wear Selma out at Duff Gardens. Lisa begins to hallucinate after drinking some "water" in an aquatic ride (under Selma's order) and Bart is detained by park security. After these negative experiences caring for Bart and Lisa for a day, Selma decides she can live without children, and adopts Jub-Jub, Gladys' iguana, instead (until Goo Goo Gai Pan, when she adopts Ling Bouvier, but still keeps Jub-Jub too).