Deep in the bowels of a factory late at night, two people are seen arguing. The noise of the machinery makes it impossible to tell who is speaking or what's being said, but the argument rapidly heats up... and ends with one of the participants pushed into the running mills. Also the first episode not to be based on any of the novels.
- Bad Boss: Three of them, one arguably worse (running off-the-books extra shifts at the factory and skimming the profits).
- Bury Your Gays: One of the victims. Poor Mac has to pretend to a strictly professional attendance at her funeral.
- Condescending Compassion: Aunt Prudence, so very much. Phryne's application of snark when Prudence has to recant her earlier Moral Guardian high dudgeon is truly delicious."More pie, Aunt?" note
- Cutting Corners: The safety guards in the mill, which were removed to speed production and then replaced by factory staff right before the police arrived to investigate.
- Depraved Homosexual: The killer, who is very clearly contrasted with the several sympathetic gay characters in the episode.
- Destination Defenestration: The killer's second victim dies this way, exiting from a window in the factory's office tower and landing smack in front of Dot.
- Family Business: The Gaskins, brother and sister, who own the factory and continually snipe at each other.
- If I Can't Have You...: Turns out to be the killer's motive: one victim was the killer's ex-lover, the other was killed to throw suspicion on said ex's current flame.
- I Need a Freaking Drink: Mac is so badly unnerved at one point that Phryne tells Mr. Butler to skip the breakfast and bring the doctor strong coffee and a stiff one. She proceeds to chug the entire glass neat, and decidedly looks like she'd want a refill.
- Love Makes You Evil: The killer.
- Medication Tampering: One victim's medication is found to be spiked with bleach. It only partially works, leaving the victim weakened but not dead; the actual death comes elsewhere.
- No OSHA Compliance: Justified Trope given the era, since there was no government agency to implement workplace safety precautions. This also forms a plot point: the Bad Boss had removed the safety guards on the factory machinery to speed production, which made it all the easier for the killer to strike.
- Not Herself: The normally unflappable Dr. Macmillan is particularly hard hit upon responding to the emergency call at the factory for one of the victims, and requires a rather stiff belt of whiskey before she can talk about the case at all, let alone look at the crime scene photos. There's a reason for that: she was romantically involved with the victim.
- Not Wanting Kids Is Weird: The Gaskins use their clout with the hospital board to try and get Mac suspended from practice at one point, using this as the excuse: that she's distributing "indecent and unnatural" advice to the factory women on contraception.
- Room Disservice: Dot gets a job as a tea lady at the factory in order to rifle through the Gaskins' account ledgers. As a result, she finds the evidence of the cooked books long before anyone else.
- Sickbed Slaying: Attempted, with adulterated medications.
- The Butler Did It: Loosely played. The killer isn't actually a butler, but otherwise fulfills the trope.
- Vomiting Cop: Hugh loses his breakfast, and yesterday's lunch, upon seeing the gruesome scene at the factory. As a result, his report has quite a few holes in it, which Phryne promptly points out as an excuse to start her own sleuthing.