Looking back, it was a mistake to use blank pages of my late mother-in-law’s diary for the children’s Christmas lists. I might easily have found unused paper elsewhere, but by Advent I had torn out so many of the entries that the spine was feathered. There seemed little reason to preserve what was left of it.

I sat on the raised hearth in our living room, where the fire crackled and the tree glinted with lights and ornaments, and extracted three unmarked sheets, one for each girl. Our eldest daughter had taken colored markers from a drawer in the kitchen. Fresh from the bath and pleased to be swishing about in her new white flannel nightie with its “real” lace collar, she held out a hand.

“Mind where you step,” I said. With a glance towards the fireplace, she nodded, then doled out pens and paper to her sisters who, like her, wore the nightgowns their generous, thoughtful Nana had bought for them.

I leaned back and threw the rest of the diary into the fire. As the paper caught, the spine writhed and the glue bubbled and like a fool, I thought, that’s that, and then my husband was leaning in behind me, adding more wood, and the diary sank from view. The fresh pieces of pine snapped and popped, and I shifted to a sofa to avoid the heat.

We had never gotten around to putting a screen on our fireplace. When we had a fire, it was our practice to push the grate right to the back, to reduce the chances of burning bits spitting into the room. More than once we had been alerted to an incipient housefire by the smell of burning hair, and the Turkish carpet near the fireplace was pocked with charred areas where we had trod out errant embers with the soles of our shoes. When a fire was going, I didn’t like the girls to walk on that carpet in their soft bare feet. The idea of the hiss, the burn, the scream—it was too distressing. Better to maroon them on the upholstered furniture a safe distance away until the blaze settled.

The sight of the girls filled me with placid contentment. Rosy and sweet, the two elder daughters were writing with great diligence; their preliterate little sister was tucked up on the sofa next to her father and seemed to be drawing the things she wanted. My husband and I shared a look. It was wonderful to be alone like this, together, in the pre-Christmas glow. When his mother was alive, it was a pleasure she had not permitted us to enjoy.

As soon as my husband and I became parents, my mother-in-law had established herself as a fixture of our Yuletide scene. Every year she arrived in early December, often staying into the New Year. She came with us when we shopped for a Christmas tree, usually chose the one we bought, and oversaw its decoration when we got it home. Most of the ornaments on the tree were trinkets she had selected.

When the girls were old enough to enter school, my husband’s mother accompanied us to all their holiday pageants and concerts. She was a superior cook and took over our kitchen for whole afternoons, clicking around in her heels while she made spiced cider and her Christmas specialty: gingerbread cookies topped with lumps of crystallized ginger. She delighted the girls by pretending that they were important helpers, her elfs, and last year had dressed them in white culinary jackets with their names embroidered on the breast pockets. There was a photo of my mother-in-law smiling possessively with her arms around the girls, who were lined up on the kitchen counter in miniature chef’s toques. “My babies,” she called my babies.

Her prolonged visits had caused some early friction between my husband and me, but eventually I had accepted the futility of resistance. It was unpleasant even to try to begin to discuss whittling down her time with us. The smallest hint of demurral caused her an injury. The holidays weren’t holidays without family, she said, by which she meant herself. She was the grandmother, which was true to the extent that she was the one of two grandmothers who did not live abroad and was not frail. If, as happened a few times, I or my husband suggested modest changes to the annual plan, she shifted with alarming swiftness from hurt to anger—but this only happened, as I say, a few times. If she was not crossed, my mother-in-law could be excellent company. We preferred not to cross her.

When she got sick, things moved quickly. Nana was a beauty. She did not wish to be seen, even by us, during her sudden and rapid decline. “Let my babies remember me as I am,” she said to her son over the phone, ruling out a farewell visit. There was plenty of money to pay for care. Hired nurses would give her morphine when she needed it and handle any unpleasantness at the end.

Packages began arriving at our house: a food hamper with a plum pudding, a jar of hard sauce, and marzipan fruits wrapped in foil; boxes of books for the girls; more boxes containing the flannel nightgowns. All the tags read: “Merry Christmas! Love, Nana.”

Before she died, my mother-in-law wanted to make sure she would still be present in our future. Now here we were in that future, which was in some ways the loveliest of presents, and her influence was evident everywhere in the room. Quite how much influence she still had—how much presence she retained—was not yet plain to me. But I was to learn.

“Don’t look,” our eldest daughter said, as finished her list and folded the paper to conceal her writing.

“It’s a surprise for Santa,” agreed the middle daughter, imitating her sister’s actions.

The little one saw the way things were going, and folded her note up, too. The eldest collected the lists.

“Is it safe?” she asked me.

The fire had settled. I gave her a nod. On tiptoe, she reached up and put the lists on the mantlepiece, facing down, so that her parents would not see.

After our daughters were in bed, my husband and I returned to the sofa to read their Christmas letters. We were Santa, after all, even if the girls didn’t know it yet.

“She’s been wanting a princess dress and a crown,” I said, recognizing the eldest daughter’s list as my husband unfolded it and held it out for us to read:

Merry Christmas, Santa! Please will you bring me 1) Nutcracker, 2) Sell fone, 3 Nana.

“A cellphone, already,” said my husband. “And—that’s odd.”

“No princess dress,” I said. I felt a curl of unease.

We looked at the middle child’s note, written in unsteady cursive:

Dear Santa. My list is nutcraker, choklets, Nana.

We opened the final note. Our youngest had made the blocky shape of a man. Another nutcracker. She had drawn a second blocky figure with a triangular skirt and feet that seemed to have talons, or spikes.

“How very odd,” my husband said. “Nutcrackers? All three of them? And Nana.”

“Nana,” I said, feeling sick.

“Maybe they don’t understand that she’s gone,” my husband said. “They never got to say goodbye.”

“Well they’re old enough to know that Santa can’t bring their dead grandmother back for Christmas,” I snapped.

“You can hardly blame them,” he replied. “She has been with us for Christmas every year of their lives. She’d be here now if she could.”

In the end, the girls got what they wanted. So, horribly, did Nana.

On Christmas morning, with the fire crackling again, our daughters ransacked the packages under the tree and rejoiced to find that, among other tantalizing goodies, Santa had given each of them a slightly different wooden nutcracker figurine with painted teeth and a jointed jaw.

“Mine is Simon!” cried the eldest. “Nana told me.”

Simon.

My throat constricted. I recognized the name.

“No fair,” the middle girl yelped, “You can’t have Simon. Mine is Simon! Nana told me!”

“Cinnamon!” said the little one, to be part of things. It made the older girls laugh.

“That’s right, your nutcracker is Cinnamon. Mine is Simon,” said the eldest, nuzzling the toy in a way that seemed too romantic for a girl her age.

“No, my nutcracker is Simon,” the middle daughter insisted, setting her fists. She was getting angry.

“What’s all the fuss? Who’s Simon?” said my husband.

He didn’t know. He hadn’t read Nana's diary.

After his mother’s body had been taken to the crematorium where it was incinerated, but before it was returned to us as powdery grey particles in a plastic bag inside a cardboard box, I had opened a manila file labeled “Social Security” amongst the paperwork that my husband and I were sorting in her empty apartment. There I found, tucked between receipts, a soft-cover journal, the diary, going back back years.

That little bitch. . . . my mother-in-law had written, of me.

It was like being electrocuted.

There were other words (ugly, weak, pathetic) that were so startling to see in her fine handwriting that I went a little blind, or a little mad, because before I knew what I was doing my fingers were scrabbling at the pages to rip out the words.

My husband was in the next room. I didn’t want him to see.

I could have closed the diary and spared myself. I could have thrown it away. But I didn’t. Holding the pages away from my body, as if distance would protect me from their contents, I skimmed long entries in ink that revealed a sickening hidden self and a sickening hidden life.

Outside the covers of her diary, my mother-in-law had presented herself to the world as so vibrant, so elegant, so thoughtful—a tad controlling, yes, but people said that was part of her charm. Yet all the time, as she clicked around in her heels and laughed her pretty laugh and gaily told everyone what to do, that gleaming exterior had concealed a seething malignity, a woman full of resentment and deceit. The diary recorded it all.

I thought back to that first weekend when her son had introduced us. My future children’s future Nana had been notably cool, but over the years she had feigned warmth so convincingly that I had forgotten our awkward beginning. Now I understood it was much more than awkward. In time her initial dislike had bloomed into real loathing. She had hated me. If the pancreatic cancer that killed her had not intervened, she might well have managed, as she intended, to poison my marriage, push me aside, and put herself at the center of my daughters’ lives.

She was predatory in other ways, too. She had enjoyed the hunt and the satisfaction of inveigling other women’s men, especially Simon B—, a long-married friend of her late husband with whom, it seems, she was still involved when she died. There were other men: William S—, another old friend; Dan K—, one of my husband’s college professors; Ralph L—, the husband of a book group friend; and—

Here I felt I could not go on. But it was necessary to make sure. And I’m glad I did. My mother-in-law had hoped to seduce yet another married man, and she’d had ample opportunity. But my father had disappointed her.

This last detail made it impossible for me to tell my husband about the diary. The disclosures were too humiliating. And he had idolized his mother. She was dead. Why tell him now? What good would come of smashing his illusions? Also: Why show myself to him through her cruel eyes?

My mother-in-law and her diary were both long gone, eaten up by flame. No evidence remained of her dark, implacable hatred. There was no reason for my husband and children ever to know, and no danger that any of it would resurface. So I kept mum, which, in this context, strikes me as an unfortunate way of putting it. Because I was wrong.

The doorbell rang, and my husband got up to answer it.

“Mmmm, I smell gingerbread cookies,” said our middle daughter.

“Me too,” said her elder sister.

“Huh,” my husband said from the front hallway. “Look what’s just arrived.”

Just outside the open front door, stood a stack of beribboned boxes wrapped in Christmas paper. There was no sign of any delivery person. The street outside was empty. My husband knelt on the porch and turned over one of the gift tags.

“Merry Christmas! Love, Nana,” he read aloud.

“Nana!” our daughters exclaimed. They began to chant: “Nana, Nana, Nana!”

“Isn’t that nice, girls? She always was so thoughtful,” my husband said. His face was radiant. He didn’t know.

I found it difficult to arrange my face, so I went back to the kitchen for more coffee and retreated to the sofa by the fire.

“All right, let’s see what Nana has sent us,” my husband said.

He hoisted the stack of gifts in his arms and shouldered the front door closed. The girls capered around him in excitement (More presents! From Nana!) as he walked the length of the hallway and entered the living room.

With him came my mother-in-law. She clicked in on silent heels, tossed me a look of contempt, and sank with a graceful gesture into an empty chair. She raised her eyebrows at me, as if to ask, “Surprised?”

I went to my feet, opened my mouth, and screamed.

Hot coffee sloshed over my hand. A familiar odor floated up from the carpet.

“What on earth—?”

“Mom, what’s wrong?”

I sat back down, weak with fright and shocked by the sudden sensation of intense pain. When I stood up, I had put my bare sole on a burning ember, and the thing had sunk into my flesh.

The girls had crowded around to soothe me. The little one stroked my arm with her nutcracker and said: “Cinnamon will make you feel better. Do you feel better?”

“I do feel better,” I said, though I was in agony. The pain in my foot was the least of it. There sat my mother-in-law, whom I now knew to be my enemy. She had been reduced to ashes, yet there she sat, insouciant and triumphant. No one else was aware of her presence.

“Say thank you to Cinnamon.”

“Thank you, Cinnamon,” I managed.

Across the room, Nana held out a shapely leg and twirled her foot at the ankle. She looked at me with a contemptuous feigned pity.

“It does smell like gingerbread,” my husband said. “Did you make some?”

“Silly Daddy,” said one of the girls. “Mom doesn’t make gingerbread. Only Nana does.”

“I could make gingerbread,” I said in a weak voice, but no one heeded me. The girls and their father were too busy sorting through the gifts that his mother had arranged to be sent after she died.

There was a bottle of whiskey for my husband, and a bottle of perfume for me. There were nutcrackers for the girls, expensive European models with real feather plumes on their hats and shiny braids on their epaulets. These figurines were much fancier than the ones I had bought, so it was not a surprise that the girls immediately dropped the old ones, Simon and Simon and Cinnamon, in favor of the new models from Nana: Simon One, Simon Two, and Cinnamon Two.

My mother-in-law watched with approval as the girls took the toys to the base of the tree and began playing an elaborate imaginary game.

“It’s funny,” my husband said. “The presents. The gingerbread. It really feels like my mother is still here. You know, in spirit.”

Nana smirked at me and examined her perfect manicure.

“Well,” I said. “She is.”