When someone mentions private detectives in Victorian London, the first things that spring to mind are deerstalker hats, three pipe problems, and all-male casts. Sherlock Holmes has been the British detective default standard for a century.
Perhaps that's why the opening to Miss Scarlet & The Duke is so refreshing. There are no hidden clues or Dr. Watson to impress. Instead, there's a young woman who is paying street urchins to point her towards dead bodies so she can find a mystery to solve. But her most recent one, Delilah (Maria Guiver), turns out to be drunk, not dead.
Miss Scarlet: Next time check for a pulse first.
Miss Eliza Scarlet (Kate Phillips) is not yet a private detective. She's a wannabe, trying to impress her father, Henry (Kevin Doyle), an actual private detective since retiring from the police force. But notably, when her most significant case turns up — her own father's disappearance — Eliza defaults to the police. She asks her childhood friend (and Henry's former protege) Detective William Wellington (Stuart Martin), known to his colleagues as "The Duke," for help. Duke dismisses Eliza's worries, knowing her father is an alcoholic. He's more concerned with her tendency to steal files in her constant search for a case to prove herself.
But perhaps Duke should have taken her more seriously, as he is soon brought home by Dr. Edwards (Barry McKiernan), dead, not drunk. The poor man was found in an alley, having suffered a heart attack. As Eliza buries her father, she realizes the household is in dire straights. The housekeeper, Ivy (Cathy Belton), already reported the maid couldn't get shopkeepers to sell her basics due to how in arrears their accounts are. She has two choices: Marry the wealthy Rupert Parker (Andrew Gower), whose mother, Mrs. Parker (Helen Norton), is practically insisting on it, or find a way to turn her father's business into her own.
Luckily, a case has walked in the door, and the client doesn't know Henry is dead yet. Alfred Winters (Aidan McArdle) is looking for his daughter, Clara Simms (Elise Chappell), who has disappeared after marrying a man he declares "a degenerate." He believes her to be living a debauched lifestyle somewhere in London but has failed to find her. Eliza races to see what she can find before Winters figures out her father is dead but fails. Once he learns Herny is gone, she must prove he shouldn't take the case to a rival agency by finding Clara as fast as she can.
Eliza's regular urchin contact can help, pointing her towards a street preacher known as Padre (Sean Duggan). Padre speaks in riddles, which lead to Moses (Ansu Kabia), the manager of a local brothel and dance hall. Delilah works there too, though Eliza would rather she not remember where they've met. They all point her towards Clara, who is currently up against a wall with knives thrown at her like she's Miss Fisher. (She's not; she's terrified. As any sane person would be.)
Before she can get to Clara, Eliza has to best Moses a few times, which she does, earning his ire and perhaps just a glint of respect — the first and only person to show her any all episode. But she can't get Clara out before Wellington's boys, DS Frank Jenkins (Danny Midwinter) and PC Honeychurch (Matthew Malone), bust in with a raid and arrest Eliza. Miss Scarlet is reduced to insisting she's Duke's favorite sidepiece to get the cops to let her go. Wellington thanks her by throwing her in jail to teach her a lesson about attempting to get into this business.
It's not a glamorous exit into the street the next morning, but Eliza has still won. Clara's ready to see her dad. He was right about her husband, Joseph Simms, who was only interested in her for her money, and whom she lives in terror of finding her again. Then her "father" walks into the Scarlet offices, and Clara goes white. That's not Alfred; it's Joseph. Her father has been dead for months, and, as the next living male relative, the authorities notified Joseph. He stood to inherit all his wife's estate, just as soon as he could find her. Now that Eliza has been so kind to find Clara for him, he'll have his wife locked in an asylum and live like a king on her money.
Eliza is horrified, enraged, and also can pay her bills. She won, but at what cost? So Miss Scarlet goes to Duke, begging to help get Clara freed. Duke is enraged she put herself in the same room with Simms at all. Eliza should be thankful she got paid in money and not her life. He waves Simms' file at her; he's a rap sheet as long as her arm. She thanks him for the advice by stealing it off his desk. Surely there must be something in there she can use. The good news is there is a loophole: Joseph claimed he saw his first wife, Beatrice, die when the Princess Alice sank. But Joseph wasn't on the boat; he was in jail. He has no idea she survived, making his marriage to Clara not legal.
When Eliza confronts him with the news, Joseph threatens to kill her; she says Duke and his men are outside. Of course, she's lying, no one else knows she's here, or she wouldn't have been allowed in this room. But she's not lying about having pressured the hotel manager to give her a key to Joseph's rooms or that the maid let her fix up the tea that was served to him before she arrived, which she filled with laudanum. Eliza delivers an unconscious Joseph to the police, and Clara is free.
There's just one small matter left now, and that's Rupert Parker. Except, to Eliza's shock, his latest visit is not to propose marriage. He's "not ready" to marry, there's so much more of life and the world (and men) to see. Eliza is so delighted she tells Rupert he can blame it all on her when he tells his mother as long as he does her one favor. She needs an investor to continue her father's private detective venture. Perhaps she's going to make it after all.