These bookcases were in the gallery on the second level, which contained row upon row of scientific texts. One reached them by a very narrow winding staircase made of marble, with cherubim cut into its sides.

McConnell’s career had been proof, in its way, of the limits of money. It was Toto’s family’s enormous fortune that had allowed him to stock this laboratory, this library, but for all the years he’d had it, the pleasure he got from his work there had never equaled the pleasure he derived from his work as a practicing physician. This had been his vocation before his marriage, but her family had been too great to welcome a doctor into its midst and had been adamant that he give up his position. In the decade between that forfeiture of his career and the last year, when he had started working at the Great Ormond Street Hospital for Children, McConnell had never seemed quite himself—no matter the luxury of his laboratory. It gave Lenox a sense of relief to know that his friend, who was inclined to drink in low times, was once again content; as for Toto’s family, McConnell now quite sensibly ignored their protests. Toto herself was a willful person but more significantly a loving one. She had come to accept the new job for what it was: the best of outcomes for her husband’s happiness.

McConnell led Lenox to the tables, where a glass bowl was full of a dark red liquid. “This is wine,” he said.

“While you’re working?” asked Lenox.

McConnell smiled. “When I boarded the Gunner and saw that there were no markings on Wakefield’s body, no wounds, the first thing I looked at was—”

“His hands,” said Lenox, who had known the doctor’s methods for a long time.

“A good guess, but no—his gums. They can often tell us something about a poisoning. As they did this time, though not in the way I had expected. On both his upper and lower gums, very near the teeth, there were thin, steel gray lines. It was a textbook example of the Burton line.”

“What is the Burton line? What poison does it mean?”

“That’s what’s so interesting—I would never have expected to find the Burton line on the gums of an aristocrat. It indicates an exposure to lead.”

Lenox frowned. Lead. “Is that so unlikely?”

“Yes, it is. He was not a painter—they will go on using lead in their paints, no matter how they are warned—and he was not a metalworker. Fortunately they gave me this tissue sample.”

“What did you find?”

“Something called litharge of gold. It’s very definite confirmation that Lord Wakefield ingested lead. And I would be surprised if it hadn’t caused his death.”

“Why would he have ingested lead? Doesn’t it taste awful?”

“I told you before that lead poisoning is no longer very common. It is nevertheless famous enough that I’m sure you’ve heard of it. The reason is that for twenty centuries or so, since the Romans began the practice, human beings, idiots that we are, adulterated our wine with lead. More specifically, with this litharge of gold, which is in fact not gold but a brickred color. It sweetens sour wine and makes the flavor of it more even, or at least that’s the conventional belief. Unfortunately it also kills you. Though I should say that first it drives you insane. Nearly every mad Roman emperor was probably suffering in some measure from lead poisoning. It’s only been in the last seventy years or so that we’ve persuaded people to stop using lead in their wine and port. The benefit to the public health has been dramatic, genuinely significant.”

“So he was poisoned by wine?”

“I believe so, based on his stomach tissue. And for the first time in two millennia you can feel fairly sure that it can’t have been accidental.”

“Wouldn’t it have tasted bitter, this wine, if it were full enough of lead to kill him just like that?” asked Lenox.

“Ah, I should have been more clear. The line I described on Wakefield’s gums doesn’t indicate simply that he was exposed to lead. It indicates that he’s suffered from chronic exposure to lead. I believe someone had been poisoning him slowly for many weeks, perhaps even for months.”

CHAPTER NINETEEN

It was following this illuminating discussion with McConnell that Lenox finally returned to Hampden Lane after his long day, to find Lady Jane and Toto together with their daughters. When Toto had gone he ate a quick bite and then sat in his study, thinking. Lady Jane stayed with him there to keep him company, reading next to the fire at the end of the room, occasionally closing her eyes to drowse. Lenox, for his part, was wide awake. His mind was working, working. Eventually he pulled a sheet of paper from his desk and began to write up his notes from his day’s activity.

A slow, methodical poisoning—it stood in stark contrast to the brutal and instantaneous method of Jenkins’s murder. Lenox wondered what Wakefield’s habits of drinking had been. According to his butler he had generally eaten lunch at the Beargarden and supper at the Cardplayers. It would be necessary to inquire there about his drinking habits—indeed, they might even have his bills, showing what he drank and when. Lenox jotted down a word to remind himself to check this.

“Why would the lead have suddenly killed him just now, so soon after Jenkins’s death?” Lenox had asked McConnell in the laboratory. “I mean to say, if the poisoning had gone on for weeks, mightn’t he have died at any moment?”

McConnell shook his head. “By the time he died, he would have been inured to the taste of the lead in his wine, I expect, and whoever was poisoning him could have increased the dosage enough to kill him outright. His body would have been so toxic at that stage that any little extra amount would have pushed him over the edge.”

“A brilliant method if you have the time,” said Lenox. “I’m surprised I’ve never come across it. An ideal means for a wife to kill a husband, I would have thought.”

Replaying this conversation in his mind, Lenox looked across at his own wife and smiled. “Jane, if you had to kill me, how would you do it?”

Without opening her eyes, she said, “I’d have elephants stomp you. That’s how they do it in India.”

“It seems unnecessarily harsh.”

“You shouldn’t ask questions if you don’t want the answers.” She opened her eyes and looked across at him pointedly, but couldn’t keep a straight face, and laughed. “I could never kill you. What on earth do you mean by asking, Charles?”

“If I weren’t me and you weren’t you, I suppose I mean.”

“Thank goodness that’s not the case.”

“But if it were? Would you poison me?”

“I don’t want to think about it. This sort of thing never came up when you were in Parliament.” She looked up at the clock on his mantel. “It’s late, too.”

He stood up from his desk and went across the room to give her a kiss on the forehead. “You ought to go up to bed.”

“Aren’t you coming?”

“I have to go out again.”

“Do be safe.”

“I will, I will. You have my word.”

She squeezed his hand and stood up from the chair, her copy of Middlemarch under her arm. She kissed his cheek. “I love you.”

“I love you, too.”

After Jane had gone to bed Lenox sat at his desk again, ruminating about the case. He felt as if there were too much to do. He mustn’t lose track of Jenkins. That was crucial.

At ten forty, tired, he departed Hampden Lane in the carriage, his horses apparently again in full health. He stopped in front of Mitchell’s, where he saw Dallington just about to enter. “John,” he called from the carriage.

Dallington turned. “Ah, there you are.”

“Let’s go to Wakefield’s instead. I’ll explain on the way what McConnell has told me.”

“Right-o.”

It was too late to expect Wakefield’s servants still to be awake, and the house was mostly dim, so when Lenox rang the bell it was with the expectation that there would be a wait of some time. Instead the door opened almost immediately. Wakefield’s butler, Smith, was still dressed for his job.