Phryne is in bed with Lindsay when Lindsay suddenly proposes. Phryne asks why and Lindsay says it is time as they get on so well and he has good prospects. Phryne neither agrees or disagrees but says they will discuss it. The go downstairs for cocktails and discuss it some more and Phryne says she needs time to think but asks Lindsay to be her escort to the wedding of Amelia Sackville whose father is a racing pundit. Phryne says that according to Bert Mr Sackville made his fortune from doing down the working punter. Lindsay admires Bert and Phryne asks if she will be allowed to continue her friendship with the working classes if they are married. Lindsay says there will be no need to as she will no longer be detecting.
Lindsay asks who Amelia is marrying and Phryne says Tom Fletcher. Lindsay says he knew Tom from school and he was a ladies man. Lindsay's laughs that he is marrying the bookies daughter as he has the gambling bug. Phryne is contemplates the marriage proposal with Dot and Dot says that Lindsay would expect his wife to behave as he wished.
The next afternoon Mr Aloysius Fletcher comes to see Phryne with his secretary Smithy. He tells Phryne that the family heirloom jewels that were meant to be a gift to the bride were missing. They had been stolen from a safe in Smithy's room. Phryne agrees to try to find them and Mr Fletcher and Smithy leave.
Phryne goes to examine Smithy's room and then Mr Fletcher asks her to see his wife. In the room with Mrs Fletcher are Tom and Amelia. Amelia says she does not care about the jewels. Phryne says she will do her best and goes back to examine Smithy's room. She notices all Smithy's sketches and see she has talents. Phryne asks her if she left art school but Smithy says she never went as she couldn’t afford it. She went to work with the Fletcher's when she was 16 as her mother who was Mr Fletcher's cousin died.
By the next day Phryne had the solution to the missing jewels but was at a loss as to what to do about it. She took a walk to think about that and Lindsay's proposal. When Phryne returns home the hall is full of flowers from Lindsay. Dot asks if Phryne has made up her mind as the Butlers need to know in case they need to find a new job. Phryne tells Dot that she hasn't made her mind up yet but if she does she will still keep on the house and the Butlers.
It is the day of the wedding and Phryne dresses. While Dot is helping her dress Phryne mentions the fact that the glass was on the outside windowsill and no one would look for a 10x10 jewel case in a flat portfolio. She says she doesn't know what to do as she doesn't want a scandal at the wedding. Then she has an idea and gets Lindsay on the phone and asks him to give Tom a message to bring the jewels to the ceremony. Phryne wonders what Tom will do now she knows his secret.
Outside the church Phryne manoeuvres through the crowd to get to Smithy. She meets Lindsay who is holding the jewel case and asks what Tom said when her message was passed on. Lindsay says Tom said he was sorry but has to go through with it. As Amelia walks down the isle Smithy comes across faint. Phryne asks Smithy if it was like that at the registry office. Then she says Dot couldn't find a record of the marriage and Smithy hands her a marriage certificate from when she was 16. Phryne says that's what Tom was looking for when he staged the break in. Smithy says she loved Tom but did not sleep with him until they were married but he fell out of love with her. She says she was going to raise her objections to the marriage during the ceremony but Phryne says there is a smarter way to deal with the situation. She asks Smithy for Mr Fletcher's cheque book and leaving Lindsay to look after Smithy heads back inside.
Phryne sits next to Mr Fletcher and shows him the marriage certificate and asks for 5 thousand for Smithy to keep her quiet. Mr Fletcher is angry but begrudgingly agreed and Phryne gave the cheque to Smithy. The wedding continued without hitch.
Phryne sees Smithy settled into a nice boarding house and Smithy wonders what she will do with her life. She decides to by a house and a cat. Phryne returns to the wedding now realising that she cannot marry Lindsay and she will have to tell him and lose him. Phryne tells Lindsay but he says that seeing Smithy's plight had put him off marriage and he was happy for things to continue as they were.