Chief Wright: We have a fugitive on our hands! Fiona Flanagan escaped from custody! We thought arresting the notorious gang leader for murder was our final victory... But Fiona the "Scarlet Slayer" had one more surprise for us!
After being informed that Fiona Flanagan, the Irish gang leader who was also revealed to be the Scarlet Slayer, had escaped from justice by hiding in an opium den, Maddie and the player rush to the establishment to intercept her before she can run away for good. However, both officers receive a big surprise when they find Fiona's lifeless body lying on a couch, dead after being strangled by her killer.
Tropes:
- Ambiguous Start of Darkness: Although Fiona only started murdering prostitutes after her best friend Celia died from syphilis, the fact that she was already in a mental asylum before those events (not no mention the implications that she also murdered her own parents when she was still a child) leaves unclear just when Fiona became the deranged psychopath she was in life.
- Asshole Victim: Even if she was clinically insane and had a pretty heartbreaking Freudian Excuse for her actions, at the end of the day Fiona was still a bloodthirsty Serial Killer who believed she had the right to decide whether prostitutes had to live or not, and so her death isn't mourned by anyone.
- Back for the Finale: Adrienna Brassiere, Katherine Woolf, and Finley Flanagan all return as suspects in this case, which is the last one set in Sinner's End. Marla de Paradis also makes an appearance during the Additional Investigation.
- Big Brother Instinct: Finley's reason for taking his sister out of the mental asylum and giving her a share of his business was because he didn't want her to rot in a mad house, and also declares that he murdered her out of family love to end her suffering.
- Call-Back: Vittorio Capecchi returns as a suspect here since his last appearance in Case 12.
- The Climax: For Sinner's End.
- Cynicism Catalyst: For Fiona, losing her best friend and the only person she cared about due to syphilis was this, which prompted her to become stoical and broke her mind to the point she became the Scarlet Slayer.
- Connected All Along: As it turns out, the thugs that murdered Judge Lawson's fiance were part of the Irish gang and Fiona's henchmen, giving him a motive to become her killer.
- Continuity Nod:
- Vittorio becomes a suspect when you find a Kiss of Death heart he sent to Fiona, just like his daughter did with George Buchanan in Case 12.
- Katherine becomes a suspect when you find shavings of her Wixon CC pencil at the crime scene, which she was also shown to use in Case 13.
- Judge Lawson's dead fiancee and the obituary he keeps in his wallet is mentioned again.
- Double Knockout: Finley and Vittorio "defeat" each other during their Mexican Standoff by shooting each other in the arm.
- Even Evil Has Loved Ones: Fiona had a prostitute friend named Celia Barnes whom she cared deeply about, and her death due to becoming infected with syphilis is what finally broke what little sanity she had left and instigated her to become the Scarlet Slayer, wanting to "save" other prostitutes from the same fate Celia suffered.
- Exploring the Evil Lair: The Scarlet Slayer's lair appears as a crime scene, which is located inside of a filthy train wagon with photos of her victims and scribbles around the walls.Maddie: Did you see those pictures on the wall, <Player's Name>? There's Gladys, Caitlin, and all the other victims of the Scarlet Slayer!And the stench...! This place is worse than a pigsty! All the dirt, the rotten food... ugh. This is definitely the lair of a deranged maniac!
- Family Honor: According to Finley, he wouldn't kill his own sister just because she murdered "a few harlots", saying that isn't the Flanagan way of solving things. Instead, he killed her out of mercy due to her poor mental health.
- Foreshadowing: Evie's comment about how she's writing a romance novel where her heroine is supposed to fall for a dashing thief but can't stop thinking about her best friend foreshadows her aborted Ship Tease with Diego and how she ends up becoming an Official Couple with Katherine later on.
- Frame-Up: Unsurprisingly, Finley attempts to pin the murder of his sister on Vittorio, claiming that the death of an Irish gang leader could only be attributed to the Italians.
- Freeze-Frame Bonus: In the document detailing how Fiona was committed to an insane asylum, you can briefly see how she was sent to one located in Grim Chapel for her treatment, which you'll also be visiting in Case 45.
- Freudian Excuse: As detailed in Even Evil Has Loved Ones above, the death of Fiona's best friend Celia is what led to her going completely crazy and commencing her killing spree as the Scarlet Slayer.Adrienna: But, truth be told, Fiona did seem fond of Celia... Took her under her wing an' all. Lord knows what stirred in that wicked soul of hers, but she was kind to her, like.When Celia got poorly, Fiona paid for the doctor to come, and stayed at her bedside until she died......An' after the funeral, Fiona disappeared. Even Mr Finley didn't know where she'd gone.When she came back, she was... changed. More quiet than before. We didn't know it then, but that's when Fiona started murderin' them girls, didn't she?
- Freudian Excuse Is No Excuse: As expected, Adrienna refuses to feel sympathy for Fiona's Freudian Excuse, claiming that the murder of countless prostitutes is something that cant be forgiven.
- Gibberish of Love: Just like last time, Isaac can barely speak with Marla without getting all tongue-tied around her.
- Good Samaritan: During the Additional Investigation, you help Marla obtain ownership of the Moulin Rose cabaret so she can give the prostitutes working there a better and safer work environment, deciding to use her fiance's inheritance to do that instead of escaping from Sinner's End.
- Gory Discretion Shot: Finley and Vittorio shooting each other in the arm is obscured by a black screen that only shows them holding their arms after getting hit.
- Hated by All: Or at least hated by all prostitutes of Sinner's End, if Adrienna's testimony regarding Fiona holds some true. Can you blame them, though?
- Hellhole Prison: Stonewall Prison is apparently this if you aren't Italian (and specially if you're Irish), as the rude and hardcore Finley implores you to not sent him there, since it's apparently being controlled by the Italian mafia.
- High-School Sweethearts: Vittorio and Fiona were in a relationship when they were still young and the Italian-Irish rivalry didn't exist yet, although they were forced to break up by Vittorio's mother.
- Immoral Journalist: Katherine shows shades of this when it's revealed that she had discovered the Scarlet Slayer's hideout a time ago but didn't tell anyone about it, wanting to keep the story for herself. Maddie is understandably angry with her.
- Institutional Apparel: You find a photo of Fiona wearing a straight jacket due to being institutionalized on an asylum, confirming that she was already crazy before the death of her best friend.
- Love-Obstructing Parents: Vittorio tells you that the reason why he and Fiona broke up was because his mom didn't approve of her due to Fiona's bad temperament.
- Mandatory Unretirement: Judge Takakura is forced to come out of his retirement due to Judge Lawson becoming a suspect in this case, making him unfitting of judging the trial. He goes back to his retirement to the Bahamas at the end of the case though.
- Mercy Kill: Finley's motive for killing his sister is that she was so far gone and out of her mind that putting her out of said misery was apparently the best course of action.Finley: When you nicked her, I thought it'd do her good. I thought prison would clear her head.But when she escaped, she came straight for me, raging mad! I couldn't calm her down! I knew she was too far gone this time.I told yer, t'was an act of mercy. She was tormented, she was. It was kinder to put an end to her sufferin' than let her live like that.
- Mexican Standoff: One happens between Finley, Vittorio, and Maddie during the Chapter 3, with Finley accusing Vittorio of murdering Fiona, Vittorio defending himself, and Maddie trying to defuse the situation.
- Never My Fault: Finley refuses to take responsibility for his sister becoming the Scarlet Slayer and slaughtering countless prostitutes, even when he knew she was clinically insane but decided to take her out of the mental asylum anyway.
- Nonviolent Initial Confrontation: Judge Lawson becomes a suspect when you find his fingerprints on the Flanagan's headquarters, claiming that Fiona "invited" (i.e. forced him) to drink with her because she wanted to know who the new judge was.
- Not Me This Time: Finley truthfully claims that he didn't orchestrated Fiona's escape from prison when you interrogate him, saying that some time behind bars could've benefited Fiona and cleared her head from being the Scarlet Slayer.
- Not Proven: During the Additional Investigation, you discover that there have been claims of the Italian mafia controlling the Stonewall Prison in Coyote Gorge, but no proof has been found about it. According to Judge Takakura, he's convinced that the police corruption in Concordia is what allowed Vittorio to dispel those claims by greasing the hands of a few officers, and yout next mission is going to the prison to find out if said allegations are true.
- Opium Den: Where Fiona was killed.
- Rapid-Fire "No!": Vittorio is fond of doing these in this case in a very innocent manner.Maddie: This Kiss of Death we found among the victim's possessions makes us wonder if your "famiglia" had a hand in her murder!Vittorio: No-no-no-no-no! I'd do no such ugly thing!
- Room Full of Crazy: The Scarlet Slayer's hideout has photos of her victims and words scribbled in the walls of the wagon it's located.
- Shipper on Deck: Diego encourages Isaac to confess his feelings to Marla during the Additional Investigation, claiming that there's nothing uncouth about love.
- Shout-Out: William Shakespeare is quoted.
- Sibling Murder: Fiona ended up being killed by Finley, her own brother.
- STD Immunity: Tragically Averted regarding Celia Barnes, Fiona's deceased best friend, who died after contracting syphilis and pushed Fiona to become the Scarlet Slayer so other prostitutes wouldn't meet the same fate as her.
- Villains Want Mercy: After Finley gets sentenced to Stonewall Prison, he implores you to not take him there, claiming that he'll be dead man within a week due to the Italian mafia supposedly controlling the place. This is enough to make Chief Wright send the Flying Squad to Coyote Gorge so they can investigate the prison and allow Finley to remain on a holding cell.
- Villainous Breakdown: Fiona had one off-screen according to Finley, who went raging mad at him after she escaped from prison and nothing he did could calm her down, which prompted him to murder her.
