If I do this, Allie told herself, I am no better than Mary. I will have sunk to the worst possible place a person can go. After this moment, I will be a cold-blooded killer and it can never be taken back.

So the question was, did Allie Johnson have the strength to sacrifice all that was left of her innocence if it meant she might save the world?

The answer came to her like a burst of courage from a wellspring deeper than she knew she had inside herself.

I would sacrifice everything I am, everything I believe, to save the living world.

And so, with tears filling her eyes, she took the cap off the syringe, found a vein in Milos’s arm, and injected a massive dose of poison into his withered body.

Mrs. Vayevsky opened her eyes to see the delivery girl looking down at her.

“Are you all right, ma’am?” the delivery girl said.

Mrs. Vayevsky was now lying on the couch with no memory of how she got there. She sat up feeling weak and light-headed. “What happened?” she asked. “Have I fainted?”

“You’re fine,” the delivery girl said. “I’m sure there’s nothing to worry about.” She offered Mrs. Vayevsky the faintest of smiles and a glass of water, which she drank with a shaky hand. “You should rest,” the delivery girl said and she clasped Mrs. Vayevsky’s shoulder a little too hard, for a little too long. “I’d better be going now.”

“The package . . . ,” said Mrs. Vayevsky.

The delivery girl pointed. “It’s on the table there. Like I said, there’s no need to sign for it.” Then the delivery girl left, quietly closing the door behind her.

When Mrs. Vayevsky felt strong enough to stand, she went to the table to find the package had already been torn open. Had she done that before she fainted?

Inside, of all things, was a Russian nesting doll. Its familiar shape—like a squat bowling pin—and brightly painted surface, made her smile. It was the kind of simple wooden toy she had played with in her youth, a reminder of a much simpler time. On the outermost shell was the painted figure of an old man, but each shell opened to reveal a smaller, younger man inside, until finally in the very center was a wooden baby no larger than her pinky. The gift came with no card, no return address, no clue as to who sent it, or why. All the same, she knew exactly where it needed to go.

She headed to her son’s room and set all six shells of the nesting doll side by side, smallest to largest, on Milos’s desk, admiring the colors and the workmanship it had taken to create the lacquered figurines. Then, when she turned to glance at the bed, her expression changed.