Mr. Sinh arrived at half past five the next morning, which Mai would later learn was late for him.
She found him sitting on her father's porch with a battered thermos and a child's exercise book, the kind with a cartoon bear on the cover and a name written in careful capitals: NA, CLASS 5B.
"My granddaughter's," he said, a little defensively. "Half the pages are empty. A man should not waste paper."
Mai bit back a smile. She took a pencil from her father's drawer and handed it to him, and they climbed together while the mist was still lifting off the valley in slow white sheets. The stone steps were slick with dew. Somewhere below, a rooster argued with the dawn.
At the seventh terrace she showed him how her father had counted. One row. Twenty bushes. Three shoots on each, the same hour every visit. She turned the first leaf over and held it to the light.
"Leafhoppers. Here, and here." She pointed with the pencil. "Now look for the ones that eat them."
Mr. Sinh bent so close his nose nearly touched the leaf. His pencil was too small for his hands, and he held it like a chopstick. She watched him work down the row in silence, lips moving, tallying each shoot in a crooked column of dashes. When he reached the end he straightened slowly, one hand pressed to the small of his back.
"Nine ladybirds," he said. "Four spiders. Hoppers, thirty-one."
"Now your terrace."
His sixth terrace sat just below hers, a hundred meters of earth that had once been as healthy as any in the valley. Now the leaves curled like burnt paper, and the air above the rows held a faint sweetness, sharp at the back of the throat, that Mai knew too well. It took them twenty minutes to count the same number of bushes.
Hoppers, ninety-four. Ladybirds, none. Spiders, none.
Mr. Sinh stared at his column of dashes as if someone else had written it.
"Nothing eats them," Mai said quietly. "You sprayed everything that could."
"I know what a spray does." His voice went strange and hard, like a door closing. Then he cleared his throat and tucked the exercise book into his shirt. "What do I do?"
"Stop spraying. Let the grass grow back between the rows. Wait."
"Wait," he repeated. "While the hoppers eat my leaves."
"Two weeks. Maybe three. The spiders have to find their way back."
He looked at her the way a man looks at a bridge he has never crossed.
The motorbike reached them before he could answer. It came up the narrow path with its engine laboring, crates strapped to the back, and behind the handlebars sat a round-faced man in a clean white shirt, smiling as if he had been smiling since breakfast.
"Mr. Sinh! And this must be the engineer." He cut the engine, and the silence after the motor rushed in like water. "Mai, isn't it? I'm Khoa. I run the supply shop in the commune. I knew your father well. A good customer, right up until last year."
He said "until last year" gently, the way a man mentions a funeral.
"He stopped buying," Mai said.
"Everyone has their phase." Khoa unstrapped a crate and held up a bottle with a bright green label. "New formula. Works in three days. I'll let you have it on credit until harvest, Mr. Sinh. No interest. Because we are neighbors."
Mr. Sinh's hand moved, almost on its own, toward the bottle.
"May I see the label?" Mai asked.
"Of course." Khoa's smile did not change by a hair.
She turned the bottle slowly and read. The active ingredient. The dilution rate. And at the bottom, in print so small she had to tilt it to the light, a waiting period of fourteen days between the last spray and picking the leaves.
"How many days before harvest did you spray last time, Mr. Sinh?"
"Five," the old man said, and stopped.
Nobody spoke. A bird called from somewhere in the lower rows, bright and unbothered.
"Your father was an educated man too, in his way," Khoa said at last, setting the bottle back in its crate with exaggerated care. "Look where it got him. Alone on a hill, counting insects." He swung back onto the bike. "The offer stands. Think it over."
The engine coughed to life and he was gone down the path, trailing a thin blue ribbon of smoke.
Mr. Sinh stood very still. "I owe him eleven million," he said, to no one in particular. "From the spring."
Mai said nothing. Anything she could say would sound like the lecture she had promised herself she would never give again.
That night she turned her father's house upside down.
She did not know what she was looking for until she found it, on the highest shelf of the pantry, behind a jar of dried mushrooms: a shoebox wrapped in plastic, and inside it three more notebooks, older, their covers soft with age. She carried them to the kitchen table and opened the newest under the lamp.
The handwriting was the same square, careful hand, but the entries grew thinner toward the end, and the last few were different. Shorter. Heavier with pencil.
October 14. Sprayed the seventh terrace in the morning. Wind from the east.
October 19. The children were playing on the path. Sinh's grandson, nine years old. He ran through the rows.
October 21. The boy is home from the hospital. It was my sprayer, my terrace, my wind. Sinh does not know it was mine. He thinks it was the dealer's batch.
Mai read the last line three times.
I will not spray again. I will not tell him. God forgive me, I cannot.
She closed the notebook. Through the kitchen window, in the dark below the house, she could see a single light burning on the sixth terrace, where an old man sat awake, bent over a child's exercise book, counting something he could not yet bear to understand.