This week's Endeavour begins with an advert for The Jolly Rajah, the upcoming general election of 1970, and Stanley Nayle's (Ted Robbins) wrestling tourney. The Bombay Strangler (Harki Bhambra) fights Sloane, the Noble Brother (Graeme Stevely), as Win arrives with her pal Bridget (Flora London).
The point is evident even before the British Movement speech from Martin Gorman (Jason Merrells), demonizing immigration and inciting boys like Gary Radowicz (William Allam) to gang violence. (The "color of your passport," a pro-Brexit line, is especially pointed.) .
Bright: He orders an Indian meal and then butchers the man who delivers it. What is he, a lunatic of some sort?
Thursday: Food critic, sir.
The gang incident ends with Gary stabbing a Pakistani boy, and his mother (Rebecca Saire) hides the blood-soaked evidence, lying to Thursday and Morse when they come to investigate. As Thursday searches for Gary, Morse gets redirected. Nuha Sardar (Hiftu Quasem), daughter-in-law of the family running The Jolly Rajah, reports their delivery man, Aziz, disappeared. Owner Uqbah Sardar (Madhav Sharma), is verging on dementia, so his brother, Rafiq (Pal Aron), hands Morse the address list of the final deliveries of the evening. The last one leads to Aziz's body inside a flat belonging to TV chef and food critic Oberon Prince (Neil Roberts).
Last week ended with flasher Jakobssen's death, and Bright wants to connect these stabbings, especially as the gang victim and Aziz were Pakastani, but Thursday disagrees. The Jolly Rajah isn't part of that, Nuhar's husband, Salim (Shane Zaza) is struggling to hold things together with help from his brother, Farook (Sia Alipour), a local physician, who also happens to be the doctor attending to Bright's wife. Prince is nowhere to be found. His neighbor, a divorcee, named Ilsa Trent (Deva Wareing), swears she heard nothing. Frazil says Prince files his columns well ahead so he could have been missing for weeks. She then heads off to an inquest dealing with a freak accident, the sixth in as many months.
Morse heads back to the office, where he discovers Thursday is obsessing on the Andrews case, even as Blish is going to trial. It's getting the better of him, as Thursday has taken to stalking the towpath, and Carl Sturgis as well. Thursday's towpath fixation is lucky for Uqbah, who wanders off in the middle of the night, and turns up there, lost, soaked, and crying. On the way home, Uqbah suddenly says he believed Aziz was stealing from the till. He never said anything, feeling guilty over how little they paid.
At the flat, Morse finds a bloody thumbprint and a gambling chip matching one found at the gang stabbing. Rosemary Prince (Emma Cunniffe), Oberon's ex-wife, arrives. She confirms Oberon orders Indian; he was into gambling and could be abusive after drinking, but this is "beyond his scope." (She also suggests their marriage ended because he wasn't into women.) But Strange discovers Prince's bill for that night is dine-in, not takeaway. Salim recognizes Prince's photo and confirms he was there that evening. He also had an incident with some regulars, a rowdy table of wrestlers. The wrestlers are sans their main star Sloane when Morse stops by, but confirm Prince was there, drunk, and attempted to make a scene.
Thursday traces cars parked outside Prince's flat, hoping to catch him, but instead discovers Farook having an affair with Ilsa. They met via Isla's father, who runs an underground card game. Prince played regularly, as do the Sardars. That's awkward, as Isla's dad is Martin Gorman. Gorman sneers he'll play with anyone with money. He also reveals Prince won big recently; his description of the opponent suggests it was one of the Sardars. Ilsa isn't the only one facing prejudice. When Farook tells Salim he's in love with a white divorcee, his brother is furious. Salim has joined a nationalist movement, planning to move "home" to Pakistan, despite being born and raised in England, much to Nuhar's distress.
Prince's body finally turns up, stuffed in his own suitcase. If that weren't enough, the kid Gary stabbed also passes, and the Pakastani youth take the law into their own hands, attacking Gary and killing him, leaving his mother devastated. At the autopsy, DeBryn notes Prince's killing was competent butchery, whoever did it knew their way around a bone saw. The bloody thumbprint comes back as belonging to the wrestler Sloane. But the wrestling star's story explains the "incident" at the restaurant was Prince covertly getting his attention for a tryst. Sloane went over expecting sex, walked in, saw Aziz's body, heard sawing from the bathroom, and fled in terror.
Morse realizes the address called in ahead of Prince's was fake, to stall Aziz, so that the killer could get to Prince's flat first. Tracing the calls back, the one for Prince's order and the one just before came from the same number, matching the phone box behind the restaurant. Strange says they'll have to question the whole family, but Thursday and Morse shake their heads. The only member of the family who never sees the customers, and wouldn't know Prince had already dined in that night, is the cook: Uqbah's brother Rafiq.
Rafiq comes quietly. He admits he is a gambler, £13k in the hole to Prince, and the one stealing from the till. Rafiq justifies it by saying the restaurant's profits are his by right. He had a verbal agreement with his brother to split 50/50, only to have it all evaporate when Uqbah's memory began to fail. Aziz figured out Rafiq was stealing and gave him a chance to come clean; killing Aziz and framing a dead Prince solved both problems at once. The shock to the family changes Salim's mind about leaving. He agrees with Nuha to stay in England and take over the restaurant, before wishing Farook well in his marriage to Ilsa.
On the night of the election, Gorman uses Gary as a rallying point, but his mother won't have it, slapping Gorman across the face, saying he's as responsible for Gary's death as the men who stabbed him. Meanwhile, Ludo's back, claiming his wife is traveling, convincing Morse to visit. But Violetta is there when Morse arrives, creating an uncomfortable evening. She attempts to smooth things over; Morse rebuffs her. But when she comes to his flat, he breaks and resumes their affair. As for Thursday, he agrees with Morse that he's gone round the bend and gives up his patrols of the towpath. So, of course, another woman is murdered there on her way home.