Warning: Contains spoilers!
This episode kicks off with Mrs and Mrs Johnson being murdered on the dock and after the killer takes a pocket watch their bodies and luggage are thrown into the ocean.
Phryne is driving to Queenscliff with Aunt Prudence, Dot and Jane. As she pulls into town she has to break suddenly to a man who runs in front of her car whilst being chased by another man.
Meanwhile back at the station Jack and Hugh are reading a newspaper article about Benitos lost treasure being found. Jack who is a coin collector says that he thinks it is a genuine Spanish doubloon.
The boy servant (Kip) mentions a burglary as Gerald McNaster (Hilly's son) comes out of the house following a policeman and asks the policeman why he wont believe him. The policeman says the coin was handed in and Gerald must prove ownership and in the absence of any evidence of a break in there is nothing he can do.
Gerald greets the party and Prudence tells Gerald that Phryne is a private detective so they all go into the house. As Phryne and Dot enter the house carrying a basket of champagne they see a sign stating the household is a temperance household so they return the champagne to the car.
Back in the drawing room Aunt Prudence asks why Hilly let the Johnsons retire and asks where the vases she gifted Hilly have disappeared to. Hilly tells her she has moved them to her bedroom.
In the study Phryne asks Gerald if he thinks the theft and the Johnson's departure is linked. Gerald says small items have been going missing around the house but the Johnsons were always devoted servants. Phryne asks what else is missing and Gerald says he hasn't noticed anything else.
Phryne tells Hilly that she thinks the Johnsons are thieves and Hilly says she doesn't understand why they would suddenly starts stealing after years of service. Phryne says perhaps they need the money but Hilly says she doesnt think so as they introduced her to the temperance union.
Dot and Jane go to make tea with Kip. Jane goes into the pantry to make sugar and notices a bed roll in there. They hear yowling at the door and the Johnsons dog appears.
Back in the drawing room Phryne tells Hilly the police should be informed of the Johnsons disappearance but Hilly says she cannot believe they are thieves and Gerald tells her that the policeman will be no help. Aunt Prudence suggests Phryne ask Jack. Dot calls Phryne to the kitchen and tells her about the dog appearing back at the house. Kip and Jane go to ask around to see if anyone has spotted the dog around town.
Phryne phones Jack and asks about the doubloon and the disappearance of the Johnsons. Phryne asks Jack to find proof that the coin belongs to Gerald.
Phryne, Jane and Kip are on the beach. People are digging for more of the treasure. Phryne notices a dead body on the beach. Kip calls the police and Phryne uncovers the body which she thinks has been deliberately covered up. Phryne recognises the man as the one that ran in front of her car that morning and a bystander, Ellis tells her it is Frank the Fish, the fishmonger who used to crew on his boat. Phryne finds Mr Johnson's pocket watch on the body.
The policeman arrives and tramples all over the crime scene. Phryne tells him that the men knew the deceased and she say one of them chasing Frank and that the body had been covered. Phryne calls Jack to investigate as it is clear that the policeman is incompetent. Phryne tells Jack to come to Queencliff.
Dot is on the station meeting Mr Butler and noticed rattling crates being loaded onto the train. Dot informs Mr Butler of the murder. Kip arrives and Mr Butler gives him an old suit to help Kip become a proper butler. The trio head to the house.
Jack talks to the sergeant who says the temperance league were bad for business. Jack asks the policeman to find out where the Johnsons were going and who saw them.
At dinner Kip looks dashing in his proper Butler uniform. Aunt Prudence ask Phryne if she thinks there is a connection between the murder and the Johnson's disappearance. Jack tells them it is mere speculation. Jack asks to speak to Gerald and Hilly says he is in his study looking for a mold he took of the doubloon.
Back in Melbourne Cec drops the bottle of liquor to Hugh. Bert comes into the station very drunk at 9am. Bert says the liquor fell of the back of the train and it was very strong.
In Queencliff Dot is taking inventory of the silverware and notices many item of silver missing. Kip tells Phryne that Mrs McNaster used to buy her fish from the fishmonger and paid him in kind with items from around the house. Kip says he told the Johnsons about it and they tried to talk to Hilly but she made a big fuss about it. He says this was not long before the Johnsons left.
Phryne tells Prudence that Hilly is in financial difficulties. Aunt Prudence asks Phryne if she thinks Hilly killed the fishmonger and Phryne says no but she thinks the whole thing is linked somehow. Hilly arrives downstairs and asks how the inspector is doing. Aunt Prudence tries to ask Hilly about her money problems but Hilly is very short with her. Kips arrives to announce luncheon.
At lunch Hilly looks ill. Gerald and Jack arrive and Phryne asks them if they have had any luck with the Johnsons. Jack says not yet. Gerald says the sergeant is also causing them problems as he has shipped the coin to a museum for authentication. Jack joins them for breakfast and Phryne asks about when the next full tide is. Jack says very early morning.
Early the next morning Phryne and Jack sneak out to the docks. They see the boat being tied up to the docks and find a place to hide. The men are unloading crates from the boat.
The next morning in Melbourne Hugh calls Jack with the result of the analogy of the liquor. He says it is a lot more potent than normal rum and is bootleg. Jack tells Hugh to come to Queencliff. Hugh lets Cec unlock Burt from the cell where he was sleeping off his drunkenness and asks them about the liquor. They say they didn't know it was bootleg as the guard on the train told him it had come straight from the brewery. They picked it up when they picked up the parcel off the train for Miss Fisher. Hugh says the bottle was the parcel and it is the same liquor found on the dead man in Queencliff.
At breakfast Phryne notices Hilly sneaking a drink of alcohol. Hilly reprimands Kip for serving breakfast on the dinner silver but Dot informs her that the breakfast service is incomplete. Jack arrives for breakfast and tells Phryne about the liquor that Cec and Burt witnessed being offloaded from the train in Melbourne. Phryne says they must find a link between that and the crates they saw being offloaded on the docks. Phryne opens the drawer and find Hilly's stash of liquor. It is the same rum.
Jack and Phryne go to meet Hugh at the pier and arrive in time to see the bodies of the Johnsons washed up on the beach. Jack goes to speak to Ellis as he overhears a woman saying she heard Ellis arguing with the Johnsons. He asks Ellis about the cargo he was unloading the night before. Phryne asks the woman about Ellis' argument with the Johnsons. Ellis tells Jack and Phryne that he was arguing with the Johnsons as they wanted a ride as they had missed the ferry and he had refused. Hugh arrives at that moment.
Back at the house Phryne informs Hilly of the deaths of the Johnsons. Gerald enters with his doubloon which he says the police eventually gave back to him. Phryne tells him about the murders.
Jack and Phryne go to the morgue and get the autopsy reports. Mr Johnson has been killed by being stabbed through the stomach and Mrs Johnson had been suffocated. Phryne wonders if the Johnsons had threatened to expose Ellis and his crew for illegal smuggling of rum.
Phryne goes to see Sterling and tells him Ellis has turned him in. Sterling says he knows nothing about any rail deliveries or smuggling and neither did Frank the fishmonger. Phryne wonders what Franks connection was to the bodies of the Johnsons and Sterling says Frank had nothing to do with it. Sterling tells Phryne the argument was about the fact that Ellis would not give the Johnsons a ride and nothing else.
Jack and Phryne hide under the pier and hear Ellis arguing with Sterling about the fact Sterling let Frank the fishmonger have a few cases of the rum. Sterling tells Ellis that Frank was going to talk about the smuggling operation so he had to kill him to shut him up. A fight ensues and Ellis pulls a knife the police stop the fight and arrest Sterling for the murder of Frank. Ellis throws the knife into the sea. They also take Ellis in on suspicion of killing the Johnsons.
At the station Ellis is questioned and he says that half the town hated the Johnsons. He says they blamed him for supplying Hilly with the rum. It was in fact Frank's little sideline. Ellis says Sterling must have killed the Johnsons too as he was the last one at the pier. He said Frank and him had dumped the bodies in the sea. Phryne asks where Ellis got the knife he pulled in the fight and he says he found it on the pier. Ellis is taken to the cells and the sergeant says he thinks Ellis is guilty as no one would clear up after a murder they didn't commit.
The sergeant then gives Jack a telegram from the Melbourne museum which is a response to his coin inquiries. It says a doubloon minted in 1798 went missing from their display a few years back. This doesn't help them as Gerald's was minted in 1790.
Back at the house Aunt Prudence goes looking for Hilly and finds her passed out in the bath. Prudence calls for help and Dot and Phryne arrive and take her out of the bath and put her to bed. Prudence said she thought Hilly had drowned and Phryne said she almost did, in rum. Hilly tells them the rum was medicinal at first and then she needed it. She said she couldn't let Gerald know. She said she was paying the fishmonger in items from around the home as he said he would tell everyone about how hypocritical she was. Hilly says the Johnson left as they tried to help her and she lapsed back into drinking once to often. Hilly said she paid them with Geralds coins. Gerald said he had no idea. Hilly said she can't remeber the night the Johnsons left and the cards or the coacoa as it is all a blur.
Phryne asks Kip about Gerald making Hilly coacoa and Kip says no coacoa was made as it would have woken him from his sleeping in the pantry. Phryne then asks Dot if Hugh brought his bathers and Dot says she will ask.
Phryne, Jack and Hugh head to the beach and Jack and Hugh go swimming in search of the knife Ellis threw into the sea. Hugh find the knife and Phryne says it looks like a collectors piece. She heads back to the house and checks Gerald's study and notices their is a knife missing from his display and the dagger fits the space perfectly. Phryne then searches and find the doubloon and see it is dated 1798 She calls Jack at the station and tells him the dagger belonged to Gerald and Jack asks how it got to the pier. Phryne says that Gerald had not been truthful about the coacoa and thinks he was doing something else that night like chasing up his doubloon or rather doubloons. She asks what year the museums doubloon was minted and Jack tells her but then Gerald enters the study and cuts of the call.
Gerald pulls a dagger and Phryne asks him why he stole the museums doubloon. Gerald says the museum deserved it as the refused to fund his adventures. Phryne asks why he killed the Johnson's for a box of coins and Gerald says the coins were his and the greatest find of his career. He tells Phryne Mr Johnson would not had over the coins. Gerald says when he read about the museum coin being found in the sand it was his reprieve.
At that moment Jack calls out to Phryne and Phryne hits Gerald around the head. The next morning at breakfast Mr Butler announces the car is packed. Hilly asks where Jack is and Phryne tells her he has gone back to Melbourne to return the doubloon to the museum. Hilly says to Prudence she was never good enough for the grammar school and Gerald's arrest just proves it. Prudence says she will stay on and help Hilly face society.
Phryne and co drive back to Melbourne. Back in Melbourne and at her home with Jack Phryne says she think it is a shame that Gerald achieved extraordinary things and then ended up in jail. Phryne ask Jack where he got his coins and Jack said he inherited them from an uncle and sold them to buy his first bike.