This week's Miss Fisher's Murder Mysteries begins with a stylized cold open of a couple murdered at the ferry at Queenscliff. It's great timing since that's where Miss Fisher is heading right now in her fabulous car, with Prudence, Dot, and Jane in tow. It's a busy time in the holiday town, with the Temperance Movement holding protests, thieves being chased across the street in front of Fisher's car, and a valuable and rare Spanish doubloon turning up on the beach.
Miss Fisher: No mean feat to close down a watering hole in a fishing town.
When Miss Fisher pulls up to Hilly McNaster's (Julia Blake), where they are staying, the place is in an uproar. The family's servant couple, Clive and Moira Johnson have unexpectedly retired with no warning. Worse, the house has been burgled, or so Hilly's son Gerald McNaster (Dan Wyllie) claims. The Spanish doubloon found was stolen from him. Rather than leave, Prudence starts talking up Phryne's detecting abilities, and with only Kip (Reef Ireland) to run the house, Miss Fisher promises Mr. Butler will come down for the time being, and Dot volunteers to help too.
Fisher heads to investigate Gerald's study. The globe-trotting explorer says there were no signs of burglary; he knew he'd been robbed after the story in the paper of the doubloon, and discovering his entire coin collection, mostly finds from Peru, was gone. It's not the only thing missing; silverware and ornaments have been slowly disappearing too. Fisher wonders if the petty thievery might be linked to the Johnsons' exit. But Gerald insists they were devoted to his mother. They were the ones who introduced her to the Temperance Union. They hired in Kip when his parents died, and let him sleep in the pantry when he needs to. But the most prominent sign the two didn't disappear by choice: Their dog is here, waiting for them to come home.
The local Sergeant, Baxter (Tony Rickards), is no help, as he doesn't like the McNasters. Hilly's Temperance chapter got the Baxter family hotel shut down last year. He claims the dubloon is part of the "lost treasure of Queenscliff." Lucky for everyone, Jack is a numismatist (coin buff) and read about the discovery. Once Fisher finds a body washed up on the beach, he's game to come down, especially when Fisher points out the body was hidden deliberately. Having a Chief Inspector also gets information out of Baxter, who calls the Johnsons' Temperance Union bad for business in a town that needs tourism.
The body is Frank the Fishmonger, the thief Fisher saw being chased when they arrived. The chasers, Wally Stirling (Jasper Bagg) and Finlay Ellis (John Brumpton), admit they laid him off recently. Fisher unwinds a watch chain from Frank's hand, which Kip says is Mr. Johnson's, and slips the half-empty bottle of booze on him into her bag. Cec and Bert are sent to Melbourne with both for Collins, still back at the shop. Bert is plastered upon arrival, suggesting the stuff in the bottle was potent indeed. Meanwhile, Butler has gained Kip's trust, and the kid tells Fisher Hilly bought groceries directly from Frank, paying him with household items like candlesticks. The Johnsons knew, and there was a big fuss about it not long before they left.
There are human bloodstains at the ferry, and the Johnsons never caught their boat. Jack and Phryne check out the next full tide to see what washes in. It's Wally and Finlay, and the clink of bottles says a bootleg operation is already in progress. Collins also learns, once he sobers up, Bert didn't drink the evidence. He bought a bottle at the train station when a shipment arrived, not realizing it was the same stuff. Jack orders Collins to join him. The timing is perfect, as the Johnsons have just washed up on the beach. One of their Temperance friends starts yelling she saw Finlay arguing with the Johnsons the night they disappeared, but he insists they just wanted a lift to Sorrento because they'd missed the ferry, and he refused.
Dot confirms the bootleg operation is not just the boat; she saw the train conductor signaling to Wally to load boxes of bottles when she picked up Mr. Butler. And Bert's not the only drinker of the stuff. Fisher catches Hilly sneaking a drink before spiraling out at Kip. When told about the bodies, she collapses in horror. Hilly blames herself, gets super drunk in the bath, and nearly drowns. She admits she started paying for the booze in household items because Gerald was monitoring the household finances since his return. The Johnsons had quit in horror when they learned of her lapse, and she'd paid them severance with Gerald's coin box.
Fisher and Jack decide to divide and conquer by telling Wally and Finlay the other had ratted them out. It elicits confession: Wally says he sold Frank cases, not realizing he'd sell them in town and get caught. Frank was about to own up, so Wally killed him. Finlay admits the Johnsons also blamed him for Mrs. McNaster's alcoholism, which he hadn't understood since he didn't know about the in-town side hustle. Finlay swears he did not kill them — he thought Waly must have when he found their bodies and a dagger when arriving the next morning with Frank. (He tossed the knife when Collins and Jack arrested him.)
Hugh and Jack change into bathing suits in the show's most gratuitously female gaze scene to date to find the dagger. It's a collector's piece, just like the ones in Gerald's study. In fact, there's an empty spot, just the right size. Add in that his story about making his mother cocoa and then going to bed is bogus; Kip never heard him in the kitchen that night. Also? There are two dubloons: he'd stolen a second one from the Melbourne museum, which he was desperate to cover up. When confronted, he admits he flipped when his mother said she gave them away. Johnson dropped the box when he chased them down, spilling the coins through the boardwalk slats, and Gerald went nuts and murdered them in a rage.
Prudence decides to stay on and look after Hilly as Fisher and Jack head home to drink openly and responsibly.