In bygone times, on a snowy night in Eastern Europe, the Jew Velvel returns to his village after selling geese at the market. Cheerfully, Velvel tells his wife Dora that he encountered Traitle Groshkover and invited him to visit. Aghast, Dora claims that they are cursed, then explains that Reb Groshkover died three years ago from typhus. What Velvel really saw, she says, is a dybbuk , or a dead soul looking to inhabit a live person. When the old man arrives, he explains that he recovered from his illness and denies Dora’s accusation that he died. Velvel assures Groshkover that he is a “rational man” and does not believe in superstition, but, to prove her point, Dora stabs Groshkover in the chest with an ice pick. After Groshkover walks out into the night with blood on his shirt front, Velvel exclaims that they will be ruined when his body is found. Dora, however, praises the Lord and says, “good riddance to evil.”
In 1967, at a Hebrew school in a Midwestern suburb, thirteen-year-old student Danny Gopnik listens surreptitiously through an earpiece to music of the rock group, Jefferson Airplane, playing on his miniature transistor radio. When the teacher discovers his inattentiveness, the radio is confiscated, along with a twenty dollar bill tucked inside the radio’s cover. On the bus after school, Danny tells his friends that the money was intended for Mike Fagle, a fellow student and bully from whom he bought marijuana. Meanwhile, Danny’s father Larry, a college physics professor applying for tenure, undergoes a thorough medical examination. The physician, Dr. Shapiro, asks about the family and Danny’s upcoming bar mitzvah, then states that Larry is in good health. Later in his classroom, Larry enthusiastically writes formulas on the board as he lectures to his bored class about Schrödinger’s Paradox, an illustration of an esoteric quantum physics principle featuring a cat in a box. Afterward in Larry’s office, Clive Park, a South Korean student who failed his examination, insists that Larry pass him, so that he can keep his scholarship. Clive explains that he understands about the cat, and only has trouble with the mathematics, but Larry argues that it is the math that is important. When Larry refuses to raise his grade, Clive departs, but leaves behind an envelope containing several hundred dollars. That evening, Larry discovers that Brandt, his gruff, “goy” neighbor, has been mowing part of the Gopniks’ lawn. Larry’s unemployed brother Arthur, who has been sleeping on the Gopniks’ sofa, is in the bathroom draining a sebaceous cyst on his neck. This annoys Larry’s daughter Sarah, who complains that she needs the room to get ready to go out for the night. After dinner, Larry is grading papers, when his wife Judith stuns him by saying that she wants a get , a ritual Jewish divorce that would allow her to marry their older, widowed and well-to-do friend, Sy Ableman. At the office the next day, Larry delays answering several phone messages from a stranger, Dick Dutton, and from Sy, in order to confront Clive about his bribery attempt, but Clive feigns ignorance about the money. At home, as Danny is practicing for his bar mitzvah, Sarah, who has been thinking about getting a "nose job," bursts into the room to accuse him of taking the money she stole from Larry’s wallet. When Larry arrives at home, Judith nags him about seeing a lawyer, Sarah whines that Arthur is in the bathroom and Danny complains that their television set is not picking up the program, F Troop . Later, Larry tries to relax, while Arthur works obsessively on what he calls “The Mentaculus,” a probability map of the universe that he has notated as intricate diagrams in a composition book. However, Sy, a paunchy middle-aged man with a smooth voice, arrives bearing Bordeaux and insists on hugging Larry. He murmurs, “Such a time, such a time,” and assures Larry that they will be “fine.” After school the next day, Danny and a friend break into the principal’s office to get his money, but discover that the radio is missing from the drawer where confiscated items are kept. Unable to pay and afraid that Fagle will beat him up, Danny runs home, with the bully in pursuit. That evening, Larry climbs to his roof to adjust the television antenna. From this vantage point, he spots another neighbor, Mrs. Samsky, sunbathing in the nude. During the night, Larry, who now sleeps on a cot in the living room, awakens to see the gun-toting Brandt leave for a hunting trip with his son. Later in the day, he sees that Brandt is preparing to build a shed partly on Gopnik property. At work, Arlen Finkle, the head of the tenure committee, drops by to inform Larry that they have been receiving anonymous letters accusing Larry of moral turpitude, but assures him that it will have no bearing on their decision. After Judith and Sy convince Larry that he should move into a motel for the good of the family, he reluctantly packs. Clive’s father arrives at his house and, threatening a lawsuit, accuses Larry of “defamation.” Illogically, Park denies any wrongdoing, but simultaneously claims that Larry’s failing of Clive prompted his son to bribery. Although Larry tries to point out the flaws in his reasoning, Park tells him to pass Clive and “accept the mystery,” then leaves. During the weekend, Larry discusses his marital problems with a friend, who suggests that he talk to a rabbi. Although Larry makes an appointment with Rabbi Nachtner, he is instead greeted by Scott, an inexperienced, but earnest young junior rabbi, when he arrives. After hearing Larry’s troubles, Scott suggests that Larry look at the world with a fresh perspective and urges him to admire the parking lot. When Larry meets with his divorce lawyer, besides discussing his marital problem, he mentions Brandt and is referred to Solomon Schlutz, a lawyer with expertise in property issues. The appointment is interrupted by Danny, who calls to complain that F Troop is “fuzzy.” On his way to work the next day, Larry is involved in a three-car accident, and arrives at work, unnerved and shaken. Dutton calls and explains that he works for the Columbia Record Club, to which Larry is four months late on paying a first installment. In vain, Larry argues that he never ordered records, but his conversation is interrupted by another call from Danny, who admits to placing the order. As Judith wails in the background, Danny tells Larry to come home, because Sy was killed in a car accident and because he needs to fix the television antenna. A few days later, when Larry meets with Nachtner, he says he feels it is not right that he should pay for Sy’s funeral, as Judith demands. Finding it strange that he and Sy were in accidents at approximately the same time, Larry asks what Hashem, or God, is saying to him. Nachtner tells him a long-winded tale about a dentist who discovered Hebrew letters spelling “help me” inscribed on the back of a “goy” patient’s teeth. When the story ends without a conclusion, Larry demands to know what it means. Eventually Nachtner suggests that helping others would not hurt him. After Sy’s funeral, the Gopnik’s are sitting shiva , when police arrive to issue Arthur a warning for illegal activity. Larry then learns that Arthur has been using his Mentaculus to win at the gambling table. After Larry learns that Judith has cleaned out his bank account, Larry’s attorney tells him that she has hired an aggressive law firm that may make the divorce difficult. When Larry begins to cry, his lawyer suggests that he meet with the highly esteemed, elderly rabbi, Marshak. However, the elusive spiritual leader now only congratulates the bar mitzvah boys each week and Larry is refused an appointment with him. In the classroom, Larry explains that the Uncertainty Principle is proof that one cannot really ever know what is going on. He adds that, despite not knowing, the students are still responsible for it on the midterm examination. After the class ends, Sy appears and says that mathematics might be subtle and clever but not convincing. He bangs Larry’s head against the wall and tells him to see Marshak, awakening Larry abruptly from his nightmare. Larry visits Mrs. Samsky, whose husband is always out of town, and offers his services, explaining that he has been advised to help others. She invites him in and introduces him to marijuana. As they talk, they hear a siren. Outside, Arthur is arrested on charges of solicitation and sodomy at a sleazy bar. When Larry later tells his attorney that Arthur claims he went to the bar only for a drink, he is given the name of a criminal law attorney. Schlutz, who has determined a way to get around Larry’s property line problem, arrives to discuss it, but abruptly suffers a heart attack and dies. In his office, the stress-filled Larry evades calls from Dutton. When Finkle drops by, Larry exclaims, “I am not an evil man!” Finkle agrees and tells him not to worry. Later, immediately after having sex with Mrs. Samsky, Larry is in a coffin with Sy looking down at him. When Sy tells him that “nailing it down” is important, Larry awakens in the motel from another nightmare. That day, Larry tries again to get an appointment with Marshak by going to his office in person. As he begs the secretary to let him in, he rambles about how he has tried to be “a serious man” and do right, but that he has lots of problems and is desperate for help. Although the secretary tells him Marshak is busy, Larry can see through the doorway that he is idle. During the night, Larry awakens to Arthur’s cries. When Arthur runs out of the motel room to the swimming pool, Larry follows and tries to comfort him. Arthur claims that it is not fair that Hashem has given Larry a family and a job, and nothing to him. They drive together to the Canadian border, where Larry gives Arthur the envelope of money from Clive. After promising to contact him when he is settled, Arthur rows away in a canoe, but is abruptly shot by Brandt, who is on a hunting trip. Brandt then points his rifle at Larry and tells his son, “There’s another Jew.” Before being shot, Larry awakens in the hotel room with Arthur, having only ventured as far as the pool the night before. On the night of his bar mitzvah, Danny smokes marijuana with a friend and feels unsteady when he begins his part of the ceremony. However, after a shaky start, he performs the ritual well, making his parents proud. Judith whispers an apology to Larry for the trouble they have had and tells him that Sy respected him so much that he wrote letters to the tenure committee. Afterward, Danny meets with Marshak to receive his congratulations and words of wisdom. After a silence, the elderly rabbi, who is quoting lyrics of a song by the Jefferson Airplane that are familiar to Danny, asks, “When the truth is found to be lies and all hope within you dies…then what?” After naming several of the musicians in “The Airplane,” the rabbi returns Danny’s radio and tells him to be a good boy. The following week, Finkle drops by Larry’s office to hint that his tenure application will be accepted. Despite the rain outside, Larry’s luck seems to be improving. Danny is again listening to his radio during class, when a tornado warning prompts the principal to order the students to proceed to the synagogue’s cellar. Meanwhile, after receiving a bill from his attorneys for $3,000, Larry changes Clive’s grade to a C minus. Just then, Dr. Shapiro calls, asking Larry to come immediately to his office to discuss the results of an X-ray. On the school parking lot, as the principal fumbles with the cellar keys, Danny notices that a funnel cloud is heading directly toward them.