As I hurried back into Studio C, I found my dance teacher, Ms. Ferri, sitting in a chair, adjusting the straps on a pair of stilts. Ms. Ferri was a tall woman in her fifties with frizzy brown hair. She had risen to principal dancer at the HDC, so she had danced some of the most important roles. Then, after retiring from dancing, she’d become the ballet mistress at HDC.

Ms. Ferri was so nice that I couldn’t help wishing she taught ballet at my school, Anna Hart School of the Arts, so that I could have her all week instead of just on the weekends. But Ms. Ferri was too busy conducting the daily class for the HDC’s professional dancers. And this year, she was busy rehearsing her own role in The Nutcracker, too—the role of Mother Ginger.

Ms. Ferri’s stilts were made out of metal rods about a yard high. In New York City Ballet’s version of The Nutcracker, men played Mother Ginger because the costume was so big and heavy. But Ms. Ferri was tall and strong enough to handle it. After years of playing Mother Ginger, she was a pro at managing the costume’s weight while she walked on stilts. No one would see the stilts, because she’d wear a skirt big enough to hide them—plus eight kids.

Ms. Ferri glanced my way when she heard the door to the studio close behind me. “Where have you been, Isabelle?” she asked, but she didn’t wait for me to answer. Instead, she turned to the other seven boys and girls in the studio. “Places, everyone. I want to run through the complete dance, so no matter what happens, keep going, okay?”

Bracing her hand against the wall, she carefully rose on her stilts until she towered above us. All eight of us gathered around her. Except for Luisa and Renata, I didn’t know the other dancers, because they came from other schools.

Luisa was my best friend and went with me to Anna Hart. Renata went to school with us, too, but she and I got along like cats and dogs. It didn’t help that I had beat her out for the role of Gingerbread Girl in The Nutcracker. Renata had been cast in another role, but she was my understudy. That meant that if anything happened to me, she would play my part. And I could tell by the way she looked at me during rehearsals, she was pretty much hoping something would happen to me.

I tried not to think about that as I stood shoulder to shoulder with Luisa and Renata in front of Ms. Ferri. More castmates lined up behind her until we formed a ring around her. Then we all hunched forward, our hands on our knees as if we were in a low tunnel. It was the opposite of all the graceful ballet positions we had learned, but it was the only way we could fit inside the big costume skirt that Ms. Ferri would wear as Mother Ginger.

When we had begun rehearsals two weekends ago, I had assumed we would practice the scenes in order. Instead, we had been split into groups that rehearsed at the same time in different studios. While I was practicing my routine in Act Two, my sister, Jade, was learning to be Clara in Act One. It was like making the individual beads separately and then later stringing them together in order for the final production.

The Nutcracker begins with a Christmas Eve party. A girl, Clara, receives the Nutcracker—a soldier carved from wood—as a gift. Put a nut in its mouth and move a handle, and the nutshell is broken so that you can get the nut inside.

After the party ends, Clara goes to the living room to get the Nutcracker, which has suddenly come to life. She finds the Nutcracker and toy soldiers fighting an army of mice. Clara throws a slipper at the Mouse King, who turns to see who threw it. And the Nutcracker kills the distracted mouse and shows his true form, a prince.

In the original production, the prince then takes Clara to the Land of Sweets, where there are all sorts of entertainments in her honor. But this year Mr. Kosloff was creating a brand-new version, so the prince was going to take Clara to the Land of Dreams instead. That would let Mr. Kosloff blend in short fairy-tale dances, like the “Runaway Gingerbread Cookie,” with audience favorites from the old version, like the “Dance of the Sugar Plum Fairy,” while the prince and Clara watched.

The gingerbread cookie part was where I came in. Mother Ginger baked a cookie—me—who ran away. I had to leap out from Mother Ginger’s giant skirt, and my castmates were going to be different characters trying to catch me.

“Claude, if you please,” Ms. Ferri said, motioning to the rehearsal pianist.

Claude, a music student at George Washington University, was so tall and thin, he looked as if he were made of toothpicks. As he started playing the piano, Ms. Ferri began to keep count by clapping her hands. From the corner of my eye, I saw Luisa’s lips moving as she kept count, too. On the fourth count, Ms. Ferri began stamping her feet. I was used to the metallic thud of her stilts by now. When she’d done that four times, she announced, “And we begin.”

She stepped toward her right, and when her left foot joined her right, the rest of us took a step to the side—all of us keeping our strides about the same length. When we brought our feet together again, she took another sideways step in time to the music. If someone had peeked into the studio, they would have thought we were baby crabs out for a walk with our mother.

During the first rehearsal, my castmates and I had tripped over one another, and there had been a lot of kicked shins and stomped-on toes. But after two weeks, we were synchronizing into a smooth unit.

Finally, we reached that point in the music when Ms. Ferri stopped. “We have landed,” she announced. “And up goes the skirt panel. And out goes Isabelle.”

This was it—the moment I’d been waiting for. As I took a couple of steps through the imaginary opening in the skirt, I pictured that big chest of toys. The one right on top was a jack-in-the-box. I sprang straight up into a jeté, imagining a child shrieking happily.

Kicking off on my left foot, I swept my right foot in front of me. At the same time, I brought my arms down so that my hands were inches from my legs and raised them in front of my waist.

When I landed, I put my legs together and arched my back.

“Great acting, Isabelle,” Ms. Ferri said encouragingly. “Keep doing what you’re doing.”

The compliment made my heart leap. So far I’d managed to do everything pretty well. I was determined to do the rest exactly right and prove to Ms. Ferri—and to Renata—that I deserved this role.

When Ms. Ferri, as Mother Ginger, began waving for me to come back to her, this Gingerbread Girl shook her head and jumped away.

“Put up your arms when you land!” Ms. Ferri instructed as she shot her own arms up into the air. “And remember to celebrate! Hooray for the Fourth of July! Merry Christmas! Happy Arbor Day!”

So the next time I landed after a jump, I raised my arms and grinned as if I were enjoying every holiday rolled into one. I began to move away in a series of leaps along a broad, curving path. As I circled counterclockwise around the room, the others danced away from Ms. Ferri in a clockwise direction. Each of them stopped at different places. They were the characters who were supposed to try to catch me.

The first up was Emilio, playing the part of a police officer. When he spotted me, he rubbed his stomach as if he were starving and tried to grab me. I was supposed to pirouette away from him.

I’d been practicing pirouettes for years, but lately I’d been having trouble with them sometimes. As I pictured the spinning toy top, I positioned my feet carefully. Spin, I told myself.

I rose on the ball of my right foot with my left leg bent and began to turn. I wobbled a little as I spun away from Emilio, but it was so slight that I hoped no one noticed.

The next character was a freckle-faced dancer named Agnes playing the role of a milkmaid. She rubbed her stomach hungrily just as Emilio had done and then stretched out her arms.

This time I was determined to get my pirouette perfect. I ran through all the steps—beginning with finding a spot on the wall. Each time I finished my spin, I stared at that same point to keep from getting too dizzy. But I was so busy running through my list of steps that I forgot to smile.

“Don’t look so grim, Isabelle,” Ms. Ferri instructed. “Feel the joy.”

I pulled the corners of my mouth up into what I hoped was a grin, but it probably would have scared small children.

Whirl like a top, I told myself.

Raising my left leg again, I began to turn. Though I tried my best, I felt myself tilt ever so slightly. Agnes’s hands twitched as if she was getting ready to steady me.

She wasn’t the only one who’d noticed. Renata, playing the role of a duchess, was my next stop. As she rubbed her stomach, she whispered, “How’d you get this role, Dizzy Izzy? It should’ve been mine.”

I’ll show you who should be the Gingerbread Girl, I retorted in my mind. As I started my third pirouette, I decided that I must have been going too slow with Agnes. Spin faster, I told myself. But I immediately lost my balance again and fell right into Renata’s arms. She seemed just as disgusted by that as I was.

“Catch and release, Renata,” Ms. Ferri ordered.

With a smirk, Renata pushed me away. “What are you supposed to be, anyway?” she asked. “A human bowling ball?”

I heard giggles from some of the nearby dancers. Renata’s teasing wasn’t going to improve my pirouettes. What was I doing wrong?

I managed to get through my pirouettes with the next three castmates, but if I’d been graded on those spins, I wouldn’t have scored over a C+. By the time I reached Luisa—the seventh and last dancer who was supposed to catch me—I decided that this pirouette was going to be the spin of spins.

Luisa stood with her legs crossed, smiling slyly. Her character—a fox—was supposed to ignore me, but she gave me a little nod to encourage me. Then she deliberately looked away.

I danced all around her, trying to get her to notice me. When she lunged forward to snatch me, I tried to pirouette away. But again I lost control and would have crash-landed if she hadn’t caught me.

“Upsy-daisy,” she whispered as she shoved me back onto my feet.

Ms. Ferri held out her arms and fluttered her fingers. “All of you, come to Mama,” she said.

But I’d thrown off the others’ timing as well as my own, and the music ended before we could reach Ms. Ferri. I shuffled to a stop with the others.

Ms. Ferri scratched her nose. “Well,” she said and then repeated more slowly, “wel-l-l, this is what practices are for: to work out the mistakes.” Was she looking right at me when she said that? I was pretty sure she was.

Renata deliberately bumped me as we returned to our original spots to try the routine again. “Watch your step this time, Bowling-Ball Belle,” she whispered.

I fought the wave of anger rising in my chest. Why did Renata have to be in this cast? She wouldn’t be happy until she had my role. That made me more determined than ever to perfect my pirouettes.

At first I’d thought that Mr. Kosloff had made a mistake when he had cast me for such a big part, but now that it was mine, I didn’t intend to give it up. Not to Renata. Not to anyone. I found my place next to Luisa and squared my shoulders.