There's nothing more cliché Italian that the murder of a little old grandmother in a kitchen, set to "La Donna E Mobile," but that's how Miss Fisher's Murder Mysteries rolls. The abrupt cut to Catholic imagery isn't related though; that's just Dot and Hugh at a lecture by Father O'Leary over his coming conversion.
They're lucky to be on hand, the kitchen where the murder took place is right across the street at Carbone's, and owner Guido Lupinacci (Robert Mammone), comes in crying him mother in law Nonna Luisa has been murdered. Dot and Hugh practically argue over whose boss gets called first, since the death is fresh enough that the bruises are only just coming up. It's a moot point since both Phryne and Jack arrive at the same time.
Miss Fisher: It always comes back to the food.
Guido spoke mostly Italian, but Collins caught the word "Camorra," a ruthless Italian gang. Guido's daughter, Marianna (Danielle Horvat), recognizes Dot from the church. Fisher uses the opening to offer her services, especially when Guido takes off to take the law into his own hands. Marianna says he's gone to Strano's, the rival Italian restaurant across town. Jack is already there to talk to Concetta Fabrizi (Louisa Mignone). Guido comes in with a gun, screaming her brother Vincenzo (Paul Pantano) killed Luisa. Miss Fisher arrives and unarms Guido before anyone is killed, and Jack, enraged, takes both Guido and Vincenzo to the station. But Vincenzo has an alibi; he was at the pictures when Luisa died and has the ticket to prove it.
Jack explains this started last year when Concetta's late husband, Fabrizi, attempted to burn down Carbone's. Ten days later, he was gunned down in broad daylight. As Guido and Vincenzo are released, they argue loudly in the foyer. Jack forces a truce, but Fisher, who speaks Italian catches they're discussing an incident down at the docks, which predated the Fabrizi incident. She decides to dine at Strano's, where she learns Concetta's marriage was arranged, and she knew little of her husband's business. (She also confirms Concetta is sweet on Jack.) Chef Pappa Antonio (Vince D'Amico) joins the ladies, sneering Luisa's "special dish" for the Festival of the Madonna is his family's own strati dell'arcobaleno, which she stole.
Fisher takes a late-night trip to Carbone's, where she is attacked. Guido rushes in and saves her. He insists Nonna had no stole recipes, but Fisher notes Luisa's ledger has a hefty withdrawal of £77 AUS. After spending the night with Guido, she has Cec and Bert take her to the docks where Mick Doyle (David John Watton) claims the Camorra are in the business of tinned tomatoes. There was an incident where someone dumped half the shipment into the ocean. But that's as far as he gets before gunshots ring out and Mick is felled right in front of Fisher as the head of the Camorra, Roberto Salvatore (Alex Andreas) walks in. Fisher shoots her way out, as Bert and Cec drive her away.
Guido confirms the Camorra gang have a monopoly on tomatoes, forcing restaurants to pay top price. Nonna Luisa fought back; she tossed the cans into the sea. Meanwhile, Mac turns up that Luisa didn't die from the attack, but poisoned mushrooms. Not from the strati dell'arcobaleno (which is a mushroom dish), but from earlier that morning. (Poisoned mushrooms take a few hours to hit.) Fisher sniffs out that Marianna's alibi about buying butter is a lie, and the girl admits she was actually at the pictures... with Vincenzo. He confessess they are lovers, but also insists there is no Camorra, they are a myth. Pappa Antonio interrupts and threatens Jack and Phryne to stay out of what they don't know.
Collins' conversion to Catholicism brings up a wife must obey her husband in all things. Indignant, Dot suggests she might convert to Protestantism instead as she and O'Leary prepare for Luisa's funeral. Collins is also there to make sure there are no incidents. The only altercation is Marianna slapping Vincenzo as they argue after services. But the most significant incident Jack and Phryne witness is a kiss, when Roberto Salvatore arrives and pays his respects to Antonio, revealing he's the real Godfather. But Antonio is also moved by the service, dropping something into the coffin. Dot creates a distraction so Fisher can retrieve it; it's a necklace with two photos, Luisa and Antonio.
Fisher asks Guido about it, but he says Luisa was a bitter, twisted woman. But Antonio confirms Fisher is right. That's how he knows she stole the book of recipes; it was in hopes of getting Antonio to follow her away from their disapproving families. Realizing that Luisa threatened Vincenzo and Marianna for the same indiscretion, Fisher and Jack again looked at the ticket pictures and realized Vincenzo arrived late to the movies. When he lifts his foot to have his shoe print taken, there's a bead from Luisa's rosary stuck to the cuff.
Vincenzo frantically confesses to everything. But he claims he poisoned Luisa while attacking her. He's lying, trying to cover because he knows Marianna poisoned Luisa. She had a good reason. Luisa was abusive, beating her with a rolling pin. And the £77 AUS was a steamer ticket to send Marianna to Italy, to force her to break up with Vincenzo. Luisa even threatened to have him assassinated, the same way she'd paid to have Fabrizi shot.
This solves the Luisa case, and Marianna has also given Jack to lead to close the Fabrizi case. She doesn't know who the guy is, only that he comes to the restaurant weekly. When she describes him, it's Roberto. Jack and Phryne head to Antonio, who denies it: he's arranged for Roberto to be Concetta's next husband. Roberto's been playing both families as part of his climb up the Camorra ladder. Antonio and Luisa were too blind by their obsessive hatred of each other to see it. As Jack arrests Roberto, Phryne hands over the long stolen recipe book to Antonio. The feud is over.
Cornered by the specter of losing Dot, the church's best helper, O'Leary decides maybe the church is more lenient on a wife obeying her husband than that handbook suggests. Meanwhile, freed from another horrific arranged marriage, Concetta confesses her feelings for Jack. However, he turns her down, much like Fisher turns Guido down instead of another roll in the pasta. Jack arrives at Miss Fisher's with a lovely bottle of wine.