Jack Robinson attends a crime scene whereby the victim has been murdered the arrest the murderer at the scene and drive him back to the station but all the way he won't talk and only tells them that he killed the victim over and over.
Meanwhile Phryne is home from a date with a man dancing at the Green Mill. However her date is very clumsy and has stomped all over her feet. She fights him off and doesn't allow him into her house. When she comes in she kicks off her ruined shoes and asks Dot. She asks Dot for her slippers and a small glass of green chartreuse and says it is the last time she does anyone a favour.
Dot says she recognises Phryne's date Mr Clarke's name from the papers. Phryne says that is her dates father who helped with mentally disabled people by putting them to work but was probably exploiting them and not paying them properly.
Dot reads the story from the paper which states Mr Clarke is missing and the gardener is accused of murder. Just then the phone rings. It is Lady Rose who is a friend of the Clarkes. She tells Phryne she has a commission for her. Phryne tells her it is after midnight and agrees to see her in the morning at 9am and the goes to bed.
The next morning Phryne heads to Lady Rose' house and is greeted by the maid who tells her Lady Rose is in a foul mood over the murder and that she personally didn't like Mr Clarke as he had some shady dealings to do with import and export.
Lady Rose introduces Phryne to Mrs Slade her cleaner. She says Mrs Slade's son Stevie was simple minded and worked for Mr Clarke and it is he who is accused of Mr Clarke's murder. Mrs Slade says her son wouldn't hurt anyone but he said he did it and there was blood on his collar. Mrs Slade thinks someone put words in Stevie's mouth.
Phryne asks to see the Clarke's house and Lady Rose gets ready to go out. Her maid tells Phryne that Mr Clarke was accused of smuggling goods. They go to the Clarke house, a large mansion called Camberwell.
Phryne pulls up to the house and is let in by a simple boy. She asks Lady Rose if all the staff are mentally disabled and Lady Rose tells her the Housekeeper, Butler and the Steward who looks after all the other staff aren't. She meets Sergeant Day who tells her Jack is on the case but they have no body only he bloody collar. Phryne suggests they send the collar to the lab to check if it is human blood or animal.
Inside they meet Jack and Mrs Clarke who is sat on the floor chanting. Jack tells them she has been doing that all morning and he can't get her to talk to him. Phryne asks what he wants to know and Jack says when she last saw her husband. Lady Rose asks Mrs Clarke but her answer is vague but then she sees the look in Lady Rose's eyes and tells her yesterday morning, he had a meeting with some businessmen and then he was supposed to be back for lunch and he never came.
Jack asks if Mr Clarke was worried about any business dealings or anything but Mrs Clarke tells him that her husband did not talk to her about his business. Lady Rose asks Mrs Clarke if Mr Clarke was planning on leaving her but she says no and he couldn't as he has no money of his own. She says he was always asking her to sign checks for him and he seemed a lot happier recently as he had been singing in the bath.
Phryne asks what he sang and Mrs Clarke tells her French songs. Phryne recognises the song. Jack says he has no further questions but needs to search the house. Phryne goes with him and they are shown to Mr Clarke's room by the steward (who is a hard faced man) as the butler is indisposed.
When they get there they realise the room has been cleaned and the bin emptied. They ask where the rubbish would have gone and ask to see it. Phryne searches through the rubbish and finds something important on a scrap of paper. She runs back into the house to show Jack. Phryne shows Jack the paper and says she has to hurry as it is nearly 11 already then she tells him she will meet him back at Russell Street station then rushes out of the house.
Phryne says that Lady Rose' maid was right that Mr Clarke was a smuggler and the figures on the scrap of paper she found were money that was accruing from the smuggling. She said the paper is torn from a book called Famous Historical Puzzles and the title of the chapter was “The Camden Wonder”. Phryne tells them it is a favourite of hers and is about a certain
gentleman, who has had shady dealings with both sides who vanishes one night. All that is found of him is a torn shirt, stained with blood, and one shoe. The steward of his house confesses out of
the blue that he, his mother and his brother murdered the gentleman. Both mother and brother deny it fiercely, beg their relative to come to his senses, but it goes to trial. The gentleman has been gone for a year. Then the steward changes his story, tries to withdraw his confession, says that he doesn’t know what happened to the gentleman. They stop to pick up Mrs Slade and Phryne says she will continue the story on the way. When Lady Rose returns with Mrs Slade Phryne tells them the steward withdrew his confession, but they were all tried anyway.’Lady Rose asks where the body was as you cannot have a murder without a body but Phryne tells them you can and the trio were hung in the story.
They arrive a the police station and Phryne talks to Stevie. She asks if Mr Clarke was his friend and Stevie agrees and Phryne asks if Mr Clarke cut Stevie's arm. Stevie says yes it was a joke and he did it to bloody the collar. Phryne ask Stevie if Mr Clarke asked him to confess to the murder and told him he wouldn't be in trouble. Stevie says yes and Phryne tells him he has to tell the truth now as the joke is over.
At that moment Phryne hears lots of shouting and Jack is dragging a man into the station. Phryne tells the man he is Joshua Clarke and a murderer. She finds out the man was attempting to escape to France with another woman and a chunk of his wife's estate that he had persuaded to sign over to her. She tells him he is guilty of attempted murder as he knew Stevie would hang for his murder just like the characters in the book The Camden Wonder. Mr Clarke is arrested and Stevie is freed.