The Mysterious Affair at Styles: Chapter 12: The Last Link Summary & Analysis

The trial is to resume on Monday, but Poirot still hasn’t returned by Sunday morning. He finally reappears that afternoon and summons everyone in the London household, announcing that he has something important to say. He even invites Alfred Inglethorp, who has been staying nearby. When they’re all gathered, he reminds them of three things he found when he first investigated Mrs. Inglethorp’s bedroom: (1) a scrap of green fabric, (2) a stain on the carpet, and (3) an empty box of bromide powder. He explains that the green fabric was torn from a small green bracelet owned by Mary Cavendish, indicating that she entered Mrs. Inglethorp’s room through the door leading to Cynthia’s bedroom.

Everyone stirs with excitement and confusion as Poirot presses on, reminding them that Mary Cavendish claimed at the inquest to have heard the bedside table fall over. However, Poirot conducted an experiment by placing Hastings near Mary’s room and then knocking over the bedside table—and Hastings heard nothing at all. Mary, then, was actually inside Mrs. Inglethorp’s bedroom when the table fell. Poirot suggests that Mary was looking for something in Emily’s room when Emily surprised her by starting to convulse. Mary dropped some candlewax in surprise and quickly ran into Cynthia’s room, bolting the door behind her. Because she could already hear people coming, she woke Cynthia up, acting as if she’d come to do so from the hall.

Mary Cavendish says that Poirot is correct. She didn’t reveal any of this in court because she didn’t think it would help prove John’s innocence. Poirot agrees, but he also clarifies to everyone else that Mary isn’t the one who destroyed the will—the only person who could have done that, Mary chimes in, is Mrs. Inglethorp herself. Hastings can’t believe his ears. He is once again flabbergasted and voices his utter surprise, but Poirot confirms what Mary has said. After all, he adds, why would Emily Inglethorp have had a fire going on one of the hottest nights of the entire year? The answer, of course, is that she needed to destroy the will.

Poirot says that Emily Inglethorp had two conversations on Tuesday the 17th in which she used very similar language, as she spoke about a “scandal between husband and wife.” The first conversation was with John Cavendish; the second one was with Dorcas. However, she was actually talking about two different scandals. Poirot explains that Mrs. Inglethorp spoke to John at 4:00 and threatened to reveal something to his wife (who, incidentally, overheard the conversation). At 4:30, Emily made a will leaving the Styles estate to Alfred. At 5:00, Dorcas found her holding a piece of paper. Emily was very upset and asked for a fire to be made. Poirot reasons that something must have happened between 4:30 and 5:00 to make Emily want to destroy the new will.

The strange thing, Poirot says, is that Emily was alone between 4:30 and 5:00. Knowing that she had no stamps in her desk, Poirot believes she broke into Alfred’s locked desk to borrow some, at which point she found the piece of paper that Dorcas later saw her holding—a piece of paper that she wasn’t meant to see. Mary Cavendish thought the piece of paper was a letter proving that John was having an affair, so she wanted to see it. But Emily wouldn’t give it to her. Mary then found the key to Emily’s dispatch case (which had been lost that morning). She unbolted the door between Cynthia and Emily’s room with the plan of returning later that night, and she drugged Cynthia so she wouldn’t wake up as she passed through her room.

Suspecting that Mary Cavendish had drugged Cynthia’s coffee to make her fall fast asleep, Poirot had the coffee in all of the cups analyzed—but none of them contained anything out of the ordinary. When he learned that Dr. Bauerstein had joined everyone for coffee, though, he realized that there should have been yet another cup (including the broken one in Mrs. Inglethorp’s room). There was, in other words, a missing coffee cup. Furthermore, all of the coffee Poirot had analyzed contained sugar, suggesting that Cynthia’s cup was the missing one, since she doesn’t take sugar in her coffee.

At this point, Poirot shifts his attention to the cup of cocoa that Annie thought someone had spilled salt into. He had a sample of the cocoa analyzed, even though Dr. Bauerstein had already taken it to the lab—Bauerstein, after all, was only testing for strychnine. Poirot discovered that there was, indeed, a drowsy narcotic present in the cocoa. It was also present in Cynthia’s coffee cup, which Lawrence later found in a brass vase. Mary Cavendish, Poirot explains, drugged both Emily Inglethorp and Cynthia so that she could sneak into their rooms at night.

As soon as she realized that Mrs. Inglethorp had been poisoned, Mary thought she herself accidentally killed the old woman. She therefore hid Cynthia’s coffee cup in the vase, but she couldn’t get rid of the cocoa without attracting suspicion. Thankfully for her, she soon realized that Emily Inglethorp died from strychnine and not the drug Mary herself slipped into her drink. But, Poirot says, this is why the strychnine took so long to kick in: the sleeping drug delayed its effects.

Lawrence interjects to say that it all makes sense now: the sleeping drug held off the effects of the drugged coffee. But Poirot stops him. The coffee, he says, was not drugged. After all, Emily Inglethorp didn’t even drink the coffee, since it spilled all over the carpet when she set it down on the unsteady bedside table. The strychnine, then, wasn’t in the coffee. It was in Emily’s medicine. Hastings blurts out that the murderer must have added strychnine to Emily’s tonic, but Poirot reminds him that the murderer didn’t need to add it—her tonic already contained strychnine.

Instead of adding strychnine, the murderer only needed to add Emily’s bromide powder to the tonic. Poirot learned from a pharmaceutical book that bromide can cause strychnine to crystallize, leading it to build up at the bottom of a bottle. Poirot then suggests that the person who poured Emily’s tonic for her each night was careful to only serve her the liquid on top, meaning that all of the strychnine built up in the bottom of the bottle. The last dose, then, was sure to kill her, since it contained a huge amount of strychnine.

Poirot believes that the murder was clearly supposed to happen on Monday, not Tuesday. That’s why Emily’s bell was tampered with on Monday, for instance. But Emily forgot to take her last dose of medicine that night. She therefore took the fatal dose the next day, and it’s because of this delay that Poirot was able to crack the case. He now whips out a letter and declares that it was written by the murderer. The letter itself is addressed to Evelyn Howard and tells her not to worry—there has been a delay, but everything will surely happen the following day. “There’s a good time coming once the old woman is dead and out of the way,” the murderer writes, adding that Evelyn was a genius to think of using the bromide powders. The letter ends abruptly and without a signature.

As Poirot reads aloud, Alfred Inglethorp stands. “You devil! How did you get it?” he yells before lunging at Poirot, who gracefully steps aside. Poirot takes this opportunity to officially reveal the murderer himself, gesturing to Alfred Inglethorp as he careens to the floor.