Maybe it was the closeness of the room, or the dominance of the enormous screen, or the large slice of cake I’d had after a large dinner. Or maybe it was the movie itself: the pale creatures with fangs who slept in coffins, rising at night to drink human blood. Whatever the cause, about ten minutes into the movie a wave of nausea came over me.

I ran to the bathroom and had shut the door when the second wave hit. Clutching the sides of the toilet, I shut my eyes as I retched. I didn’t open them until my stomach was empty, and the spasms subsided.

The tap water was cold, and I splashed some onto my face. In the mirror over the sink I saw a wavering image of my face, white, beaded with perspiration, my eyes dark and large. I opened my mouth and splashed water over my teeth and tongue to take away the sourness, and when I looked again, the face in the mirror wasn’t mine.

Have you ever seen, in your reflection, someone else’s face? It boldly stared back at me: beady animal eyes, a snout for a nose, a mouth like a wolf ’s, canine teeth long and pointed. I heard a voice (my voice) pleading, “No, no.”

Then, just as suddenly, it was gone. My own frightened eyes gazed at me; my dark hair lay damp around my face. But when I opened my mouth, my teeth had changed; they seemed larger, the canine teeth more pointed.

“Ari?” Kathleen’s voice came from outside.

I flushed the toilet, washed my hands, pushed back my hair. “I’m okay,” I said.

Too much party — that was Kathleen’s diagnosis. “You don’t want to go home, do you?”

“Of course not.” But I didn’t want to talk all night, either. “I need some sleep,” I said.

What I really wanted was time to think. But once Kathleen turned out the lights, I fell asleep almost at once, and didn’t dream, and didn’t waken until morning, when the house came alive with the sounds of floorboards creaking, doors banging, water rushing through pipes, and a petulant voice saying, “But it’s my turn.”

I had the lower bunk (Bridget was spending the night in one of the others’ rooms), and I looked up to see that Kathleen wasn’t in bed. Then I lay back again, thinking about the night before. I didn’t want to think about the mirror yet, so I focused on the movie. It was the way the vampires moved, I decided, that had got to me. None of the other stuff — the sleeping in coffins, the crosses and garlic, the stakes in the heart — had bothered me at all. But the effortless glide, the graceful sweep to and from rooms, reminded me of my father.

Kathleen came in, fully dressed. “You have to get up, Ari,” she said. “Otherwise we’ll miss the horses.”

Kathleen said she knew me well enough now not to ask if I’d ever been to the track before. “And I’ll bet you can’t ride a bicycle, either. Am I right, Ms. Sheltered Life?”

“Sad but true,” I said.

The morning was bright but clouds of fog misted the air, cold against my bare arms. We moved briskly down the street. At six a.m. almost no one was stirring.

“This is the best part of living in Saratoga Springs,” she said. “You’ll see.”

We walked for several blocks past small houses — modern rectangles, most of them, nothing like the grand Victorians in my neighborhood — then cut across a wide lawn.

“The racetrack is over there.” Kathleen waved her hand toward more fog. “Here’s where they exercise the horses.”

She led us along a white fence. A few other people were standing, sipping coffee, waiting for something.

We heard them before we saw them. Soft thuds of hooves on turf, like muted drumbeats, and then they emerged from the smoky fog, running flat out, jockeys curved low along their necks. Two white horses, two darker ones, flashed by us and disappeared into the fog again.

“It’s a shame we can’t see more,” Kathleen said.

I was too thrilled to tell her I disagreed, that seeing a momentary manifestation of horses was far more magical than a clear view could be. Now came another one, moving more slowly — white mist parting to reveal a dark brown beauty with a black mane. Her jockey bent low, toward her ear, singing to her in a soft voice.

Kathleen and I looked at each other and grinned. “This,” I told her, “is the best birthday present of all.”

We began our walk back to the McGarritts’, heading across the grass near the stables. Kathleen was telling me about a boy she had a crush on at school; then I stopped listening.

Someone was watching me. My skin tingled, telling me so. I looked around, but saw only fog and grass.

“What’s wrong?” Kathleen said. She sounded so worried that I made a face at her, and then she laughed.

“Let’s run,” I said.

We raced each other back to the street. By then the sensation was gone.

Later that morning, Mrs. McGarritt drove me home, and Kathleen came along. Apparently Mrs. McG had reconsidered her ban, because she stayed in the car and let Kathleen help me carry my stuff inside. As always, our house was cool; the windows’ shades had been drawn against the heat.

“You have so much space,” Kathleen said, looking around my room: pale blue walls, ivory wainscotings and crown moldings, dark blue velvet drapes looped back from the windows. “And you don’t have to share with anyone. Even your own bathroom!”

She especially liked my bedside lamp, which had a five-sided porcelain shade. Unlit, the shade seemed like bumpy ivory. Lit, each panel came to life with the image of a bird: a blue jay, a cardinal, wrens, an oriole, and a dove. Kathleen turned it off and on again, several times. “How does it do that?”

“The panels are called lithophanes.” I knew because I’d asked my father about the lamp, years ago. “The porcelain is carved and painted. You can see it if you look inside the shade.”

“No,” she said. “It’s magic. I don’t want to know how it’s done.” She switched off the lamp. “You’re so lucky,” she said.

I tried to see it with her eyes. “I may be lucky in some ways,” I said, “but I don’t have as much fun as you do.”

It was the simple truth. She squeezed my arm. “I wish we were sisters,” she said.

We were coming downstairs when, below, my father passed, a book in his hand. He gazed up at us. “What a relief,” he said. “It sounded like a herd of elephants.”

He shook Kathleen’s hand. She couldn’t stop staring at him. Then he went on, toward the library.

We headed for the door.

“Why didn’t you tell me,” Kathleen whispered, “that your father is such a hunk?”

I didn’t know what to say.

“What a shame that he has lupus.” Kathleen opened the door, then turned back to me. “He looks like a rock star. Our dad looks like a butcher, which is what he is. Count your blessings, Ari.”

After she left, the house seemed larger than ever. I went to find my father in the library. He was sitting at the desk, reading. I looked at him, his chin resting on his long, narrow hand, his beautiful mouth that always seemed slightly disappointed, his long dark eyelashes. Yes, my father was a hunk. I wondered if he ever felt lonely.

“What is it, Ari?” he said, without looking up. His voice was low and musical, as ever.

“I need to talk to you,” I said.

He raised his chin and his eyes. “About?”

I took a deep breath. “About a bicycle.”

At first my father said he’d think about it. Then, a few days later, he said he’d talked it over with Dennis, and Dennis thought the exercise would be beneficial.

“I know you’re growing up,” my father said, on the day we went to buy the bicycle. “And I know you need to have more independence.” He took a deep breath, then released it. “I know these things, and yet it’s hard for me not to want to keep you safe at home.”

We were driving in his old black Jaguar — a rare event, let me tell you. He used the car once a month, if that, and he almost never took me with him.

It was a warm summer afternoon in late July. He was wearing his usual dark suit — his suits and shirts were made in London, he’d told me when I asked why he never went shopping — and he’d put on a wide-brimmed hat, dark glasses, gloves, and a scarf for protection from the sun. Someone else might appear freakish, dressed that way, but my father looked elegant.

“I’ll be ever so careful,” I said.

He didn’t reply.

The bicycle store was near a shopping mall; Kathleen and I had taken the bus to the mall the previous week, and she’d pointed it out. She and Michael had also debated the merits of various models and styles, and they’d narrowed their recommendations down to three. I had the list in my pocket.

But once we were in the store, I saw that I needn’t have bothered to bring the list. Browsing among the racks of bikes was Michael.

He blushed when he saw me. “Kathleen said today was the day,” he said. “I couldn’t let you make the decision by yourself.”

“Afraid I might get it wrong?” I said, but he was gazing beyond me.

“How do you do, sir,” Michael said, his voice oddly strained. My father had come up behind me. “And how do you know Ariella?”

“He’s Kathleen’s brother,” I said.

My father nodded, and shook Michael’s rough hand with his gloved one. “And what do you think about these bicycles?”

Later that night on the telephone, Kathleen said she was mad at Michael for not telling her he was going to the bike store. “He says your father resembles a gothic prince,” she said, her voice telling me what the words did not: that this was a good thing, an “awesome” thing, to use a word common at her house, unheard in mine.

I was struck by how easily and warmly the McGarritts liked people — even odd ones, like my father and me. Perhaps the snobbery they faced at school (and elsewhere in Saratoga Springs) made them that way? Or did something in their heritage make them instinctively friendly?

In any case, now I owned a bike, a blue and silver racer. And Dennis taught me to ride it in only a day, so that when I rode up to the McGarritts’ house, Michael was amazed. “You’re a natural,” he told me.

I hoped so. I was already thinking ahead, to the fall, when I planned to ask my father to let me take lessons in horseback riding.

With the bicycle, the whole city opened up to me.

At first I went out only with Kathleen. We had a weekday rendezvous at the racetrack to watch the horses exercise; then we’d go on downtown, where we sometimes had sodas and sandwiches, after which I’d pedal home for my afternoon lessons, and she’d head for the remedial history class at her school. Kathleen thought it unspeakably cruel that we were going to school in the summertime, but actually I looked forward to my time with my father. I liked learning.

Before I met Kathleen, I’d never even been in a restaurant. Could you imagine my father, Dennis, Mary Ellis Root, and me in an Olive Garden? We had plenty of food at home and no need to go out. But Kathleen showed me how much fun it was to choose a meal from a menu. Grilled cheese sandwiches in the soda shop tasted so much better than anything Mrs. McG made, although of course I didn’t say that.