would kill the person who had drunk this water, without your perceiving otherwise than from slight inconvenience that there was any poisonous substance mingled with the water.”
“That does it,” I said. “That does it. They were afraid to go away without killing Babe, too certain he’d come after them. She tried to make herself immune from arsenic poisoning by getting her body accustomed to it, taking steadily increasing doses, so when she slipped the big shot in Babe’s food she could eat it with him without danger. She’d be taken sick, but wouldn’t die, and the police couldn’t hang his death on her because she too had eaten the poisoned food.
“That clicks. After the row Monday night, when she wrote Joe the note urging him to make the getaway soon, she tried to hurry up her immunity, and increased her preparatory doses too quickly, took too large a shot. That’s why she cursed Joe at the end: it was his plan.”
“Possibly she overdosed herself in an attempt to speed it along,” the Old Man agreed, “but not necessarily. There are people who can cultivate an ability to take large doses of arsenic without trouble, but it seems to be a sort of natural gift with them, a matter of some constitutional peculiarity. Ordinarily, anyone who tried it would do what Sue Hambleton did—slowly poison themselves until the cumulative effect was strong enough to cause death.”
Babe McCloor was hanged, for killing Holy Joe Wales, six months later.