Monk's Halloween starts off far too atmospheric when an armored car driver is shot multiple times outside a store, but he's quickly distracted by far more personal problems when his brother Ambrose calls to tell him that their father is coming home. Monk goes back to their childhood home to wait. But why is a mysterious Frankenstein's monster trying to steal candy?
This episode includes examples of the following tropes:
- Admiring the Abomination: When Adrian describes Paul Gilstrap's Serial Killings, Specific Target plot to murder his wife, Ambrose (who's been poisoned by one of Gilstrap's tainted candy bars), nods and says, "that's a good plan."
- Bland-Name Product: The Neptune bar is an invented product, perhaps a reference to another planet-named candy, the Mars bar. A Product Placement associated with poison could be problematic.
- Celebrity Paradox: When Stottlemeyer and Disher are going over the police sketch of the gunman created based on the eyewitnesses' description, Randy comments that the sketch has an uncanny resemblance to Kiefer Sutherland. Kiefer's half brother Rossif played the bad guy in the previous episode.
- Chekhov's Gun:
- When Monk takes Julie trick-or-treating, they meet Mrs. Gilstrap, who tells them that she always eats a Neptune bar before bed. This ultimately becomes an important clue to the mystery.
- Ambrose mentions that thanks to how carefully he calculates how much candy to buy, he only had one candy bar left over from last year. It turns out that the Neptune bar he ate is the old one, not the poisoned one.
- Chekhov's Gunman:
- An example where the "gunman" is an animal; the same pigeon that Stottlemeyer shooed away from the crime scene turns up later, poisoned. It turns out to be the last clue to the puzzle.
- The Frankenstein's monster who attacked Ambrose and stole candy from trick-or-treaters was Mr. Gilstrap, trying to get back the last poisoned Neptune bar.
- Continuity Nod: Monk mentions that the last time Ambrose left his house was because it was on fire, and Monk had to pull him out, which happened in the earlier episode Mr. Monk and the Three Pies.
- Crime After Crime: Paul Gilstrap poisoned a bunch of Neptune bars to kill his wife without drawing suspicion on himself, but got caught returning the poison to the lab, so then he had to retrieve the poisoned candy. When an armored car driver ate one of the poisoned Neptune bars, Paul shot him in order to cover up the fact that he was poisoned. Then he disguises himself as Frankenstein's monster and attacks Ambrose to steal the remaining bar, which Ambrose had bought. He goes down for murder, attempted murder, and who knows what else.
- Cry into Chest: Monk sobs and leans on Ambrose's chest during the ambulance ride.
- Disney Death: Ambrose eats a candy bar that may be poisoned with tetrachlorodrine, for which there is no antidote. As it turns out, he simply ate a candy bar from last year and is having stomach cramps from the expired food.
- Empty Chair Memorial: Ambrose kept their father's study exactly as he left it for thirty years. After he seemingly failed to show up, Monk begins cleaning out the study in a rage.
- Face Death with Dignity: Ambrose when he is believed to be fatally poisoned. He calmly tells Adrian not to rush to save him because there is no antidote, asks to know why the candy bar was poisoned, and tells Adrian he loves him. The inverse happens when it turns out Ambrose just has food poisoning from expired chocolate, and the brothers and Natalie share hearty laughs of relief.
- Finger-Forced Smile: While they're waiting at Ambrose's door, Natalie uses her fingers to make Julie smile.
- Halloween Episode: The events of the episode, which include a murder and attempted murder, take place on Halloween. Randy suggests this Halloween is starting a new tradition of something nasty happening on that day.
- Heartbreak and Ice Cream: After getting into an argument with Monk about their father, Ambrose indulges in the Halloween candy he bought. However, one of the candies he eats is a Neptune bar—the same kind of candy bar the murderer tampered with.
- I Am Not Shazam: The tendency for people to call the monster "Frankenstein" instead of "Frankenstein's monster" is brought up. Stottlemeyer and Monk just call him Frankenstein, leading Monk's brother Ambrose to repeatedly correct the both of them each time they make the mistake. Ambrose doesn't seem aware this is a common mistake; he warns Stottlemeyer that calling the monster "Frankenstein" will just confuse everyone.
- It's All My Fault: Both Ambrose and Adrian Monk blame themselves for their dad abandoning the family.
- Let Them Die Happy: Ambrose, believing he's dying, asks Adrian to give The Summation, because Ambrose doesn't want to die without knowing the reason why.
- Manchild: When Natalie says Julie can't go trick-or-treating without a police escort, Julie asks Randy to come trick-or-treating with her. Randy asks Stottlemeyer for permission to do so.
- Maybe Ever After: Natalie gently turns down Ambrose when he asks her on a date because dating her boss's brother could get messy. However, she tells him "maybe" if someday she has another job. Then, at the end of the episode, Natalie asks about the date.
- Missed Him by That Much: For a while, it looks like Ambrose and Adrian's father was going to be a no-show despite telling Ambrose that he'd come. Then, while the Monk brothers went to hospital to get Ambrose's stomach pumped, he did come by, but when he saw that nobody was home, he figured that they didn't wait for him, and didn't blame them for it.
- Mistaken for Romance: Ambrose asks Monk if he and Natalie are together because it's been almost a decade since Trudy's death and because he thinks Monk is the "ladies' man" of the family. Monk tells him it isn't like that. Ambrose also remembers "girls" calling for Adrian and complimenting him all the time when he was in school. Monk tells him those "girls" were his teachers.
- Murder Is the Best Solution: No real reason is given for Paul wanting to kill his wife. For all we know, Paul is doing this murder (which if he hadn't been caught with the poison, would have dragged several innocent people down with his wife) purely out of spite.
- Nice Girl: Mrs. Gilstrap seems friendly enough when Monk takes Julie trick-or-treating at her house. She even handles Monk's refusal to take a candy for fear of germs well, saying that everyone has their quirks and citing one of her own: she can't sleep without eating a Neptune bar before bed.
- No Name Given: We never learn the name of the armored truck guard Paul shot.
- Noodle Incident: When Ambrose threatens to "tell" if Monk goes in their father's study, Monk threatens to tell their dad about an incident with a shaving kit that presumably involved Ambrose.
- Obfuscating Postmortem Wounds: The driver's gunshot wounds. Gilstrap shot him repeatedly when the man collapsed from being poisoned, in hopes that would be enough to make an autopsy seem redundant.
- Platonic Declaration of Love: Ambrose tells Monk he loves him during the ambulance ride. Given that they think he consumed a poisoned Neptune bar, it overlaps with Dying Declaration of Love.
- Pragmatic Villainy: Due to being caught putting the poison back in the lab, Gilstrap attempts to take the candy bars he poisoned out of circulation, backing out of his intended mass murder since he knew that if people died of poisoning, he'd be the prime suspect.
- Razor Apples: Paul Gilstrap planned to use poisoned Neptune candy bars to cover the murder of his wife. Unfortunately, his employer caught him putting the poison back, which meant that the police would connect him to any tetrachlorodrine poisoning deaths, and he had to get all the poisoned bars out of circulation. He got all but two: the one bought by the armored car driver, and one that was part of Ambrose's order of Halloween candy.
- Ripped from the Headlines: Paul's murder idea couldn't be more clearly based on the Tylenol murders.
- Serial Killings, Specific Target: Paul Gilstrap plotted to kill his wife with a poisoned candy bar. He poisoned several other bars in the grocery store to obscure the intended target, but had to abandon the plot after he was caught sneaking the poison back into the lab he stole it from. While trying to recover all the poisoned bars, he saw that the armored car driver had already bought one and was eating it. Gilstrap knew that if the driver simply collapsed and died in the parking lot, the police would order an autopsy that would reveal the poison in his system. Once the driver began to succumb to the poison, Gilstrap grabbed his pistol and shot him, expecting that the police wouldn't look for poison in an autopsy on a gunshot victim.
- Shared Family Quirks: Once again, it's really obvious that Ambrose is Adrian's brother given his particular idiosyncrasy about Halloween candy and insisting the guy who attacked him was dressed as "Frankenstein's monster", not "Frankenstein".
- Ship Tease: Ambrose asks Natalie out and she says she'd "maybe" be interested in getting together sometime.
- Skewed Priorities: Ambrose, after being attacked by someone trying to steal candy from him, is more worried about whether or not the attacker took more than one candy bar.
- So Proud of You: In his note, the Monks' father said he was proud of Ambrose for actually getting out of the house, not knowing it was because Ambrose had been poisoned.
- Spanner in the Works: Mr. Gilstrap's Serial Killings, Specific Target plan was derailed when one of the scientists at the lab caught him returning the poison, pressing him to scramble to get the tainted Neptune Bars back.
- Tampering with Food and Drink: Paul Gilstrap poisoned several Neptune bars in order to make the murder of his wife seem like the work of a serial killer.
- There Is No Cure: Adrian, seeing that Ambrose has eaten what he believes is the last poisoned candy bar, yells for Natalie to call an ambulance. Ambrose recognizes the name of the poison, and calmly tells his brother not to bother, there is no antidote.
- Trademark Favorite Food: Neptune Bars for Mrs. Gilstrap. Paul tries to take advantage of this by killing her with a poisoned Neptune bar.
- We Named The Dog Indiana: Ambrose was named after his father's pet turtle.
- Would Hurt a Child: The characters never point this out, but considering it's Halloween when Gilstrap tried his serial killer plot, it's very likely at least one of the victims would have been a kid.
