Evolve or die! 23

There I was, in a derelict house, up against a woman who was definitely insane. I know some scientists have suggested that mankind's control over the environment has stopped human evolution, and I defend their right to say it, but Toxic's idea of how to overcome the problem was just insane! She'd elevated Darwin's theory from a scientific theory to a religious dogma, and her definition of good was whatever advanced evolution! What was worse, she had determined to do whatever it took - meaning murder and mayhem.

"...Human evolution is stuck, Diana. It needs to move on, but we;re stopping it. What I'm doing is helping nature..."
"And how does nature like it?"
"I am an agent of nature, Diana! Your compassion's misplaced, a weakness. I kill because I have to, because nature demands it! And tonight.. tonight I shall finally begin my great task! Thousands of the unfit shall perish at the hands of Toxic! Imagine it, Diana, the beautiful advance of evolution! Progress at last, after centuries of stagnation! What shall we be, Diana? What will our children be? A few must die so that the race can survive, can flourish, can advance!"
"Wh... what are you going to do?" Diana was clearly terrified, and I didn't blame her. I'd be terrified if I was tied to a chair listening to Toxic rant about her plans to kill thousands of people. They needed help, not to be murdered.
But then, I thought to myself, Toxic needed help too. Well, I could always start that.
"I've spent millions to make sure that every drug-user in London gets a dose of the first part of my special formula. On its own it's quite harmless, but it sits in the body for years, waiting for part two."
"But if users start dying after taking your drugs, they'll switch suppliers..."
"That's the beauty of my plan, Diana. I'm going to contaminate London's water supply. All of it. So that drug users will die the first time they drink tap water! No-one will know until it's too late!"

"No!"
I chose my moment to enter the room, drawing my whip from my belt as I did so. Toxic whirled to face me. Diana smiled as she saw a rescuer.
"The Girl in Grey!" Toxic laughed. She wore a form-fitting green costume with a skull-and-crossbones motif on it. A pair of silver-rimmed goggles hung around her neck, and there was some sort of green pistol stuck in the top of one of her high boots. "I was wondering when you'd try to interfere. You don't understand..."
"I do. You're insane..."
"No, the world's mad and I am sane!"
"I prefer to think it's the other way around," I said. "Raise your hands."
Toxic smiled and began to raise her hands. I should have realised she was up to something, but I only tumbled to it when something hit me in the neck. I pulled out the dart and sighed.
"I haven't taken drugs in my life."
"Fool, I don't want you dead!"
Then I felt the tranquilizer take effect. It was fast-acting, and I passed out in seconds.