Bart and Lisa scheme to reunite Krusty the Clown with his father, Rabbi Krustofsky, who disowned him for not carrying on the family tradition.
After breaking numerous engagements, Krusty The Clown is browbeaten by his assistant into having dinner with the Simpsons as a thank-you gesture for Bart helping him get out of jail (as seen in an earlier episode). When Krusty shows up, they encourage him to relax and be himself. Taking their offer to heart, Krusty turns off his clown act and his true self comes out, which is not anything at all like the “happy-go-lucky” clown they all love. Instead, Krusty is depressed. He admits that he has been devastated ever since his father disowned him for not carrying on the family tradition of being a rabbi. It becomes obvious to Bart and Lisa that Krusty needs to make amends with his father, Rabbi Krustofsky.
Reverend Lovejoy tells Bart and Lisa that he appears with Rabbi Krustofsky on a local radio show, and gives them his address. Bart pays Rabbi Krustofsky a visit to ask him about Krusty. But Rabbi Krustofsky tells him he no longer has a son and slams the door in his face. Bart and Lisa are undaunted. They find out that the rabbi has a phone in radio show. Bart calls to pose the question, “If a son defies his father, chooses a career that makes millions of children happy, shouldn’t the father forgive his son?” Rabbi Krustofsky says “no” and hangs up on him. Next, they invite the Rabbi to a restaurant, unaware they have also invited Krusty. But when the rabbi finds out the restaurant has a non-kosher sandwich named after Krusty, he gets up and leaves.
Desperate, Bart learns passages from the Talmud that proves the rabbi should forgive Krusty. The rabbi, however, finds even more impressive passages that says he should not. But when Bart quotes a religious phrase from Sammy Davis Jr., who is also an entertainer, Rabbi Krustofsky finally sees the light, and he acknowledges Krusty as his son. They celebrate their reunion on Krusty’s television show.
Source: 20th Century Fox