The iocane powder trick with the Vizzini meta-twist

Where does this variation on Mithridatism come from?


Stop reading right now if you want to avoid SPOILERS for various mystery plots!

The other day, I was reading about the plot of the last novel Agatha Christie published before her death -- and the last Hercule Poirot novel -- Curtain (1975). I haven't read the novel, and I was unaware of this plot twist: Poirot plans to drug the killer using sleeping pills in hot chocolate; the killer anticipates the trick, so he insists on drinking Poirot's hot chocolate; but Poirot anticipated the killer's move and drugged both cups. Poirot had a higher tolerance for the sleeping pill, so the killer, but not Poirot, ended up drugged.

Of course, this is the iocane powder trick. The Princess Bride movie came out in 1987, but this trick was also present in William Goldman's novel, which was published in 1973, two years before Christie's publication of Curtain.

So was Christie copying Goldman? But Christie's novel was written in the 1940s and locked away in a bank vault for decades. Perhaps this plot twist was already present in the original? But did Goldman know about the plot of Curtain? Did he know Christie? Were the plot details known to Christie's friends? Both books have what I'll call the Vizzini twist, where the target has the idea of switching cups. But the implementation in The Princess Bride has the Vizzini meta-twist, where Vizzini follows the logical reasoning to an absurd degree -- which also supports the idea that Goldman knew of a version with a single twist.

Now the basic idea has a long history: Mithridatism is the idea of protecting yourself against poison by taking small doses (see, e.g., Terence, or The Count of Monte Cristo). The more involved idea, where you use your immunity to kill someone else (and, at the very least, distract attention from yourself), was also used a lot before 1973, for instance in Dorothy Sayers's Strong Poison, and Dashiell Hammett used similar ideas, as did Christie herself in some of her other novels (see, e.g., Peril at End House).

But I haven't been able to find any pre-1973 cases (aside from the unpublished Curtain) that had not only the iocane powder trick but also the Vizzini twist. Does anyone know of any, or have any insight into whether Goldman knew about Curtain?

NEXT: Impeachment and the First Amendment, Revisited

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  1. Inconceivable!

    Sorry...I just wanted to be first in with that.

      1. One of my all-time favorite movies. Danny Kaye was a brilliant entertainer.

      2. "The pellet with the poison is in the flagon with the dragon?" "No. They put the pellet with the poison in the vessel with the pestle. The flagon with the dragon has the brew that is true."

        The Princess Bride is a funny movie, but it doesn't touch The Court Jester for poison-themed humor.

  2. Can we compare this to the real life AZ chloroquine couple, where the husband was killed by a fatal amount, but the wife apparently took a lot less and didn't die? Or in the movie Gigi, where the woman commits suicide - again - by taking insufficient poison.

    1. That story disappeared when it became clear they drank the fish drug no because Trump said to but as part of a scheme to murder the husband. Forgot about this example of our gaslighting media. until you mentioned it...

      1. Interesting. I lost track of the story shortly after it came out. It turns out that the wife appears to be a Democrat who donated to at least one anti-Trump cause (before claiming that the chloroquine ingestion was done based on his say-so).

        No wonder those who were citing it as a valid Trump-blaming incident so suddenly shut up about it.

      2. That said, I don't believe the incident was actually investigated as or determined to be a murder case.

      3. Interesting claim. Got a remotely reputable citation, or is this just another attempt to downplay Trump-inspired stupidity?

        1. or is this just another attempt to downplay Trump-inspired stupidity?

          The woman in question was in fact a donor to a Democrat/left-wing groups over the 2 years prior to the incident in question (including the left-wing PAC "3.14 Action" that was very critical of Trump). Here are her multiple donations to 3.14 Action:

          To claim that her alleged stupidity (not knowing the difference between an FDA-approved drug and fish tank cleaner) was "Trump-inspired" makes you just as stupid as she allegedly is.

        2. And while we're on the subject of "stupidity" with regard to this incident, how about all the crack reporting by left-leaning this piece by WaPo?

          A man thought aquarium cleaner with the same name as the anti-viral drug chloroquine would prevent coronavirus.

          Or NPR:

          after the couple ingested a form of chloroquine, a chemical that has been hailed recently by President Trump as a possible "game changer" in the fight against the novel coronavirus

          The stupidity here was entirely on the left. Of course, maybe they're not as stupid as they are dishonest. I'll let you sort that one out.

          1. I usually don't agree to work the internet for people, but here is a story about how it turned into a murder investigation as well.


            It trails off after that so unclear if the investigation went anywhere, it is currently active with no updates, or it was dropped. Either way.....

            1. It went nowhere, despite the breathless claims of the Free Beacon, Townhall, et al.

              Seriously, find better sources of information. The latest thing I can find from a "real" news source is here:


              'A Mesa Police spokesman refuted reports circulating in conservative media outlets, calling them "inaccurate."'

              1. There is a brilliant irony in crying about "better sources" but then dropping a link to NBC news...

                You will also note that Yahoo news is hardly a bastion of conservative thought and many other articles with the same date stress it is a murder investigation.

                1. The relevant source is "Mesa Police spokesman".

                  Do you think NBC is deliberately and blatantly lying about an attributed quote? One that can be trivially verified? What's your evidence? (Hint: "but but NBC!" is not evidence)

                  Why isn't honest, gawd-fearing right-wing media all over such an easily-checked quote? And yet ... they're not.

                  All I hear is a combination of bleating "MSM squirrel!" and "she once donated to a Democrat", which are pretty weak-sauce attempts to shift the conversation away from Trump's banal anti-science demagoguery.

                  1. “she once donated to a Democrat”

                    She made many, many donations...totaling thousands of quite a few Democrats AND left-wing organizations, over multiple years leading up to this incident. All of them were listed in the links I posted. So I can only surmise that you were either too stupid to click them, or are a lying sack of shit.

                    1. I don't care about her donation. I completely and utterly don't care. It's not relevant to whether the Mesa PD is investigating the husband's death as a homicide, which is JtD's initial, and still stupid, assertion.

                      I mean, it's cute that you care. Knock yourself out! Enjoy your moral superiority! Yay! Go you! But it's a big, fat "whatever, man" as far as I'm concerned.

                      You even seem to agree it's not being investigated as a murder. Great, because *that's* *the* *point*.

                      Consider that a stupid person might be easily capable of all of the following:
                      1) donating to (D) causes at one point in time;
                      2) switching to a pro-Trump stance in 2016 (many (D) voters did exactly that);
                      3) believing their president, because he's the president; AND
                      4) consuming fish tank cleaner because they had a terminal attack of the stupids.

                      None of those are mutually exclusive. And #1 is not relevant to #4. Again ... I seriously do not care.

                      Trying to read tea leaves about #1 to conclusively prove or disprove #2 is a fool's errand. Connecting #3 and #4 is tenuous; I think it's their stupidity, not Trump's fault. Unlike JtD, I'd don't reflexively reach for MSM-blaming conspiracy theories every time HCQ is mentioned.

                    2. I don’t care about her donation.

                      "DonationS"...plural, as in a lot of them. And you clearly DO care about them, evidenced by your need to repeatedly lie about them.

                      It’s not relevant to whether the Mesa PD is investigating the husband’s death as a homicide

                      True...which is why my response explicitly quoted the part of your post that it was relevant to:

                      "or is this just another attempt to downplay Trump-inspired stupidity?"

                      I'm sorry that you lack the cognitive ability to grasp the link between a response and what that post clearly cites as what it is a response to.

                      switching to a pro-Trump stance in 2016 (many (D) voters did exactly that

                      It's funny how you keep accusing someone else of stupidity while demonstrating that characteristic yourself with every comment you make. Her donations were exclusively to Dem/left wing campaigns/groups (including the Clinton campaign) and ran from well before 2016 through at least December 2020. An uninterrupted 4-5 year stream of thousands of dollars in contributions ONLY to Dem/left-wing/anti-Trump groups...all clearly documented in the links that you were too stupid to click and read.

                      The complete brain-death required to conclude that she was actually taking healthcare advice from Trump should make you a candidate for organ donation.

                    3. "“DonationS”…plural, as in a lot of them. And you clearly DO care about them, evidenced by your need to repeatedly lie about them."

                      I don't care enough to look. I don't care enough to lie. I don't care. What part of "I don't care" don't you understand?

                      You're the one jumping around with some inane repetitions of "but she's a Democrat! SHE'S A DEMOOOOCRAAAAATTTTT!" as if it matters, as if it conclusively settles some ineffable issue.

                      Now, carry one with another round of "BUUUUTTTTTTTT SHEEEEEE'S AAAAAA DEEEEEMMMMMMOOOOOOCCCRRRRAAAAT !!!1!11!!1!" and continue to pwn the libz. Hope you find it enlightening and useful.

                      Or go find your binky, I don't particularly care which.

                    4. I don’t care enough to look.

                      So you're content to continue making a complete ass of yourself with ignorance-based repetition of the lie that her actions were "Trump-inspired". OK, you're stupid AND a lying sack of shit. Congratulations.

                    5. Someone’s triggered. Try a nap, you’ll feel better.

                    6. You're a mouth-breathing, window-licking moron and pathological liar. Nothing is going to help with your condition.

                  2. NBC is one of the media outlets known to deliberately and blantantly put explosives in gas tanks of certain pickup trucks to illustrate just how dangerous those vehicles were in a side impact. Why? Probably because it started getting expensive smashing them in the side and not seeing a single spark much less the desired sensational explosion they were promised from a certain "spokesman".

                    1. I remember that! A literal blast from the past!

                      Do you usually base current decisions on information that's 3 decades old?

                  1. Seems like an OK source, generally agree that it supports the MesA PD statement above and provides more context and detail.

                    And I wonder if JtD can say something substantive instead of blaming the reporter when facts inconveniently disagree with his internal monologue.

                    1. And I wonder if JtD can say something substantive

                      I was wondering the same thing about you. Or if not substantive, at least something honest and not moronic as hell.

                    2. I am growing increasingly curious what your point is here.

                      I mean, I concur with your citation to something, we seem to agree on the way-way-way back point, and to you it’s an opportunity for another content-free insult. What joy does this spark for you?

                    3. I am growing increasingly curious what your point is here.

                      That you're a mouth-breathing, window-licking moron and a pathological liar. It really isn't that complicated.

                    4. But hey, you asked! Substantive question time.

                      Let’s stipulate that what’s her-name made donationS to Democratic/left/eeeevil/whatever causes. Done. Put that fact Q aside.

                      What does that fact, stipulated for this Q, actually mean to you with respect to “could she have believed trump?” That seems to be where we butt heads. Can you assign a relevance number here for your apparent belief that she’s lying:

                      0) not relevant, not admissible in a court of law
                      1) marginally relevant
                      2) highly relevant but not dispositive
                      3) by itself, more likely than not
                      4) by itself, clear and convincing
                      5) by itself, proof BRD
                      6) by itself, as certain as atomic decay

                      Me, I’m about a 0.5 - I doubt it would be admissible evidence under the FRE, and if it is, it’s not terribly relevant. You obviously differ; do you go all the way up to 6?

                    5. Me, I’m about a 0.5

                      Your IQ? That seems about right. Anyone with an IQ above room temperature understands why someone being an avid leftist and supporter of anti-Trump causes makes it pretty clear that she's not likely to be someone who bases her healthcare decisions on something she thought she heard him say (and that he didn't actually say anyway).

  3. It is a common practice for professionals that handle snakes to inoculate themselves with tiny amounts of venom to provoke an immune response in case of an accidental bite. I met a snake handler in India who practiced this for about 40 years and he said a cobra bite would produce nothing more than a mild allergic reaction in him. (He was also missing a few fingers from bites though earlier in his career). If you ever wondered where the venom came from that is used in clinical trials and to make certain anti-venoms, it involves someone manually "milking" a bunch of snakes every single day. Must be a fun job, but someone's got to do it.

  4. The Housman poem is one of my favorites. I memorized it for a ninth grade speaking contest, but ended up reciting a different poem. It was probably there that I learned about Mithridates.

  5. the implementation in The Princess Bride has the Vizzini meta-twist, where Vizzini follows the logical reasoning to an absurd degree

    Huh? The setup is quite straightforward, and there is no logical reasoning at all (as you'd expect, given that "is this wine poisoned" isn't really a question that logic can address...):

    1. The Man in Black presents two cups, one of which is poisoned. Vizzini's task is to drink from one of the cups (Vizzini's choice) while the Man in Black simultaneously drinks from the other.

    2. Vizzini realizes he has no way of determining -- by investigation or reasoning -- which cup is safe. So he attempts to trick the information out of the Man in Black.

    3. Vizzini spends a great deal of time talking about nothing in particular, looking for a reaction from the Man in Black.

    4. Vizzini arranges to swap the cups with each other without this swap coming to the attention of the Man in Black.

    5. Vizzini announces which cup he will drink from (and, by extension, which cup the Man in Black will drink from), and watches the Man in Black for a reaction. Seeing that the Man in Black appears happy to drink from his assigned cup, Vizzini is happy to drink from his own, since he knows that he holds the cup which the Man in Black believes is safe.

    This swap doesn't look the same as the swap in Curtain, in which the hypothesis is that there's a good cup and a bad cup, everyone knows which is which, and the killer demands the good cup. In The Princess Bride, there is notionally a good cup and a bad cup, Vizzini doesn't know which is which, and the swap is a tool designed to reveal that information.

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