“Then her husband was . . . sweet Jesus,” O’Malley said.
Julia nodded. “The most likely source of her infection.”
“She killed all three of them,” Tennant said. Julia heard the bitterness in his voice. “Her husband, his mistress, and their doctor.”
Julia touched his arm. “Richard . . . Louisa Allingham. You couldn’t have known. Not without the doctor’s case notes.”
“No?” he said, stony-eyed. “It seems all too obvious now.”
Julia said, “I missed so many signs.... Louisa’s miscarriages and how she always wears gloves. Mary mentioned her brother’s headaches and recent need for spectacles. And afterthe skating disaster, he was reluctant to take off his nightshirt when I examined him.”
Tennant asked, “What would you have found?”
“Syphilis lesions, most likely. I thought nothing about his reticence at the time. It was typical. Men hate to take off their clothes for me.” When O’Malley looked at her, she waved impatiently. “You know what I mean.”
“Go on,” Tennant said.
“Some doctors give their patients the false hope that mercury can stave off the disease indefinitely. But a diagnosis of late-stage syphilis is a death sentence.”
“You’re saying the so-called ‘lifetime with mercury” is a short one, and treatment is bollocks,” O’Malley said.
“Yes. Hope for Charles was gone, and concealment was difficult. The case notes show there was a conspiracy to keep the truth from Louisa.”
“Mother of God,” O’Malley muttered. “But to send Doctor Scott a poisoned bottle? He might share a glass of the stuff with someone else. Would she take such a risk?”
“Oh, I think Louisa knew her man,” Julia said. “The miserly Scott would have kept that expensive whiskey all for himself.”
“She was past caring,” Tennant said.
“Poisoned alcohol . . . Charles joked that Louisa might add Paris Green to his absinthe,” Julia said.
“Yes,” Tennant said. “He handed her the method for murdering both men.”
Julia asked, “What made you suspect her?”
“Last night, I started thinking, poison, twice in one case? I woke up convinced that both poisonings were murders. The imminent raid on the Topkapi distracted me from the obvious. A feeble excuse, I’m afraid.”
“The signs were in front of us all,” Julia said.
“It was the second poisoning that cast doubt on Allingham’sdeath as a suicide. But how to prove it? I thought the envelopes and letters might be a start.”
O’Malley said, “I saw them scattered on your desk.”
“Two handswereat work: Margot, the blackmailer; and the murderer. You had to look closely to see it.”
“You’ve a good pair of eyes in your head,” O’Malley said.
“That left three questions.” Tennant ticked them off his fingers. “Who wanted to use suicide to cover up a murder, who had access to Allingham’s whiskey bottle to add the Paris Green, and who wanted Charles Allingham and Margot Miller dead?”
“The betrayed wife,” Julia said.
“A wife who bought arsenic and lied about her whereabouts. And you, Doctor Lewis, discovered why Doctor Scott had to die, too.”
* * *
Mary stood at the door, waiting for the footman to open it. She held a box that contained Louisa’s sable muff, the one with the bloodstains sponged away. “That was quite a cut on her hand,” Mr. Petrie had said before he tipped his hat and walked away.
“My dear?”
