A couple is talking on the sidewalk when a screaming woman staggers toward them, her clothes totally ablaze. SVU is called in after the patrol officers first on the scene find the victim's torn underwear in the alley. She'd been doused with fuel oil and an accelerant, and sexually assaulted with a metal pipe.
Although most of the victim's body is burned beyond DNA testing, her feet are intact because she was wearing tall leather boots. On her foot is a henna pattern which Warner recognizes as a Muslim design. The lab salvages part of the label on the victim's burned purse; Olivia and Elliot determine that the label originally read "Atlantic Avenue Brooklyn." Among the Middle Eastern merchants in that neighborhood they locate the henna artist who did the pattern; she identifies the victim as a Mira Elbisi. Mira's husband and his mother publish a newspaper called The Arab-American, whose office is located nearby.
Olivia and Elliot visit Mira's husband at the newspaper office. Until prompted by Elliot he doesn't ask why they're asking questions about his wife, and then he asks if she's made a new complaint against him. Later, Munch and Fin interview the mother at the family home. Neither of them saw Mira the night she died, don't know where she was, and don't explain very well why they weren't particularly concerned about her. Their accounts of their whereabouts that night don't match, either.
Word of Mira's death by burning leaks to the press. Elliot learns that three weeks ago, Mira called the 7-4 precinct and said she was afraid of her husband; when officers responded, she apologized for getting the police involved. A week later a neighbor called the 7-4 because he heard loud arguing inside the Elbisis' home; that time, Mother Elbisi sent the responding officers away. The neighbor tells Olivia and Elliot he suspected Mira's husband had hit her. He also says that Mira felt stifled living with her mother-in-law, and definitely wanted more freedom. Asked if Mira had any confidantes, the neighbor responds that she was friends with a Jewish man named Joshua Friedman, who works at "some religious do-gooder group".
The religious group is the Interfaith Council, which works to "build bridges" between Muslims and Jews. Mira had kept her work with the group a secret from her husband. Friedman admits that he and Mira had fallen in love, and that Mira had told her husband she was leaving him for Friedman. That gives husband and Mother Elbisi a logical motive for killing Mira, so SVU brings them both in. While SVU is interrogating them, a report comes in of a second Muslim killed in the same way as Mira Elbisi. Victim #2 is a man, Tariq Assad, also doused with fuel oil and an accelerant and sexually assaulted with a metal pipe Since the fuel oil aspect of Mira's killing was never publicized, clearly Assad's murder wasn't the work of a copycat. Or the Elbisis, since they were at SVU's office at the time.
Olivia and Elliot learn from Assad's brother that Tariq also had been involved with the Interfaith Council. They visit Joshua Friedman again, who tells them that the previous week Mira and Tariq had participated in a Council-sponsored panel discussion about Islam, an event which had been open to the public. The Council office has heavy security, including cameras. The video of the reception following the discussion shows one attendee who seems to pay particular attention to Elbisi and Assad. A close-up of the attendee reveals a label on his jacket: "Donaghue Heating Service." Heating service = source of fuel oil.
Donaghue's owner identifies the attendee as his employee Sean Webster, who bolts when his boss calls him over and says the police want to talk to him. Sean is arrested, and explains that he ran because he'd had some trouble with the law before, as a kid. Police records show that Sean has a juvenile conviction for attacking a fellow student, a Pakistani. Also, Sean's father died when Sean was 10; afterward his mother had a nervous breakdown and later moved herself and her son from Long Island to the city.
During further interrogation, Sean displays an unmistakable hatred of Arabs which is clearly influenced by 9/11. The accelerant used in the burnings was benzene, and a search of the Webster home turns up a can of cleaning fluid containing benzene. When Sean kills a Muslim prisoner at Central Booking, Casey has to include a hate-crime charge she'd rather have left out. Enter Oliver Gates for the defense, the attorney specializing in insanity and mental defect defenses. He's also a fierce opponent of New York's hate-crime statute, and Sean's case provides a perfect soapbox opportunity. Gates hires an eminent expert who's done substantial research into a genetic basis for hatred and violence. Under her theory, Sean isn't responsible for his actions because he was born with a genetic predisposition toward hatred and violence.
At trial Gates' expert makes a very impressive presentation, while George Huang's prosecution testimony winds up possibly working both ways. When Sean takes the stand, Casey gets him to acknowledge that he hates only Arabs, not also other ethnicities such as black non-Muslims and Asians. Casey then asks him why he hates only Arabs. Sean begins explaining calmly enough that Arabs "study engineering and aviation, then use it to attack us…We fought for Muslims in Bosnia…My father fought for them in Desert Storm and died for his country…." From there Sean totally loses his cool and goes into an absolute anti-Arab tirade. The judge stops the trial until Sean can collect himself. Casey tells Olivia and Elliot to find out how Sean's father died; she needs to know whether Sean killed out of hate, or revenge.
Later Casey calls on Gates while he's visiting Sean at Rikers, and offers a plea bargain. When Gates refuses, Casey presents Sean's father Seth Webster, who is in fact alive and well and living in Detroit with his second wife. When Sean sees his father, the real reason for his hatred of Arabs comes spewing out like water from a burst pipe: Seth Webster had left his first wife and Sean for an Arab woman he met in Kuwait during Desert Storm. Sean's mother had told her son that his father died a hero in the war, but when Sean applied for college financial aid he learned his father was alive. Totally enraged at his father's abandonment and the hardship it caused his mother, Sean screams that if he had a gun right now he'd shoot his father, then go and set his second wife and their kids on fire.
With this revelation, Gates' genetic predisposition defense goes down the drain. Later SVU gets word that the Muslim whom Sean killed at Central Booking had friends: Sean's just been stabbed to death in the yard at Rikers.