A flash of amethyst silk inside the greenhouse caught his eye. Too much foliage blocked his view to identify the woman, but only one lady working at the White House was likely to wear that brilliant shade. He wandered closer, spotting Caroline as she glided among the aisles of potted herbs in the fruit and vegetable conservatory. She was with another woman, but he couldn’t tell who it was other than it was not the first lady.

Why was Caroline wandering in the conservatory at three o’clock in the afternoon? Given the casual way she strolled among the plants with the other woman, it seemed to be a social visit.

He slid toward the greenhouse door and held his hand over the mechanism to muffle the sound as he cracked it open and slipped inside. The air was warm and heavy with a green, peaty fragrance. He slipped behind a bushy screen of tomato plants to observe.

The woman was the young laundress from Croatia. Ludmila had a habit of giggling whenever his guards came into view. Most of the people who worked in the White House were single because there were no living quarters for married staff. The giggling Ludmila didn’t seem the sort of person Caroline would normally socialize with, so he slid closer to eavesdrop.

“I like apple on my oatmeal,” Ludmila said.

“Apples,” Caroline corrected. “Try again.”

“I like apples on my oatmeal,” the maid amended.

“Correct. If you like oatmeal and I like steak, that’s like comparing apples and oranges. What do I mean when I say that?”

“I know! It means they are two very different things.”

It seemed Caroline was testing the younger woman on the confusing idioms of the English language. They turned down a new aisle, and Nathaniel darted toward a trellis of squash plants to continue eavesdropping.

“If I say someone is a bad apple, what does that mean?”

“That means he is no good,” Ludmila said.

“And if someone is the apple of your eye?”

There was a long pause. Nathaniel leaned in, hoping the laundress would get it right, but this was a strange turn of phrase, and the maid struggled.

“Give me a hint,” Ludmila said.

“I was the apple of my father’s eye. He thought I was the perfect child. He blamed anything that went wrong on my twin brother, because Luke could be quite naughty, but Father adored me. I was the apple of his eye. What does that mean?”

“It means he liked you very much.”

“Correct!” Caroline said enthusiastically. She continued coaching Ludmila on quirks in the English language, using the plants surrounding them. Cool as a cucumber; low-hanging fruit; spill the beans; sour grapes.