Page 74 of The Vanished Sister

However, the bottom of the inside felt perfectly solid. There was no obvious false bottom, nor visible keyholes of any kind. Mrs. Watson lifted the box to examine it from underneath.

She could make out faint lines in the lacquer, dovetail joints at the center of each side. But the mortise-and-tenon structures were so perfectly wedged it seemed impossible that the box and the base could ever come apart.

Now Miss Charlotte reached for a biscuit. “Once upon a time I came across an article about puzzle boxes like this. It didn’t have diagrams and the directions didn’t exactly make sense…”

She took the box from Mrs. Watson, turned it over, and attempted to slide the bottom in a diagonal direction.

Nothing happened.

Undaunted, she tried it again in a different orientation. Still nothing.

“Ah, I forgot to hit it first.”

She thwacked the bottom of the box a few times and pushed from a corner. Again no luck.

Mrs. Watson, who wasn’t entirely convinced of the existence of this secret compartment to begin with, took a biscuit herself, so she wouldn’t be just sitting there watching the dear girl struggle.

“Aha,” said the dear girl. “Now I remember. The mechanism is in a corner.”

With the box still upside down, she thumped its bottom corners one by one. On her second attempt, the bottom of the box indeed slid open diagonally, revealing an envelope in an extremely shallow secret compartment.

Mrs. Watson shot out of her chair, almost choking on her biscuit. She coughed. “My G—my goodness, what is it?”

“How did you do that?” cried Inspector Treadles at the same time.

Miss Charlotte showed him a quarter-inch deep hole in a corner of the upside-down upper part of the box: In the hole was a metal ball perhaps one sixth of an inch in diameter. In the lower portion of the box that had slipped free, there was a corresponding indentation, similar in circumference, but only half as deep as the metal ball itself.

“Normally the metal ball sits in the shallower well,” said Miss Charlotte, dropping the little ball in said hole. “And its top half that sticks out serves as the locking mechanism that prevents the bottom of the box from coming apart. But even if you turn the box upside down—”

She demonstrated by flipping the lower portion over. The letter in the secret compartment fell out but the little ball did not.

“There’s a magnet!” Inspector Treadles and Mrs. Watson called out in unison.

“Correct. Which necessitated striking the box to forcefully dislodge the metal ball.”

She put the box back together, placed all the suitors’ missives inside, set the box aside, picked up the letter that had been kept hidden with such care, and handed it to Inspector Treadles.

He exhaled and accepted this piece of potentially crucial evidence for Scotland Yard. “It’s addressed to Mrs. Osmond. And it’s from—”

He squinted at the postmark. “1855. That’s thirty-five years ago.”

And there was no return address on the back of the envelope. Mrs. Watson thought there was only a single sheaf of paper inside but it contained three sheets of translucent onionskins, each densely penned on both sides, the ink on the reverse ghosting through.

As Inspector Treadles read the first page, Miss Charlotte examined the envelope, then handed it to Mrs. Watson. It didn’t look as old as the postmark would have suggested, and it smelled strongly of lavender and cedar sachets, hinting at sunless decades spent deep in locked trunks.

When Mrs. Watson looked up, it was to see Inspector Treadles sporting a nearly comical expression, somewhat reminiscent of how Mr. Broadfield had looked when he’d read the posthumous letter from his mother.

“It appears to be a note from Mrs. Osmond’s lover,” the police officer mumbled, “while she was married.”

That would be something one did not want anyone else to see, which justified Mrs. Whitehill’s caution. But why in the world did it end up in Mrs. Whitehill’s keeping in the first place, Mrs. Whitehill, who, according to Mrs. Osmond’s daughter, hadn’t even been one of her mother’s bosom bows?

The sheets of onionskin were passed down the line. Inspector Treadles leaned back in his chair, clearly trying to put greater distance between himself and the portion of the correspondence he was reading. Miss Charlotte, as usual, turned not a hair, making it impossible for Mrs. Watson to gauge the letter’s precise degree of salaciousness.

She should have trusted Inspector Treadles’s reaction.

The letter writer, deep in the throes of infatuation, first gave a kiss-for-kiss, stroke-for-stroke recital of his previous encounter with Mrs. Osmond, intermingled with extravagant compliments of her physical beauty. It was as if he’d read “To His Coy Mistress” and only remembered that “An hundred years should go to praise / Thine eyes, and on thy forehead gaze; / Two hundred to adore each breast.”

This last nearly literally. Mrs. Watson had never come across such ardent and prolix descriptions of anyone’s mammaries.