Twenty minutes after my sister drank the champagne she’d prepared for me, she grabbed the microphone at my wedding and whispered, “Mom, I can’t stand up.”

Then the microphone hit the floor.

I was still wearing my wedding dress. My husband, Ben, was beside me, cutting our first piece of cake. One hundred and twelve guests watched my younger sister, Claire, stagger against the head table, knocking over a vase of white roses.

I knew exactly why she was falling.

Earlier, I’d returned from taking pictures outside our Princeton, New Jersey, reception venue and spotted Claire alone beside my place setting. She looked over both shoulders, opened her small silver clutch, and tipped something from a folded packet into my champagne.

She stirred it with a cocktail pick and smiled at a passing waiter.

My stomach went cold.

For thirty years, Claire had taken things from me: birthday presents, credit for my work, even the apology our mother owed me after Claire wrecked my car. But I’d never imagined she’d put something in my drink.

I stepped behind a floral arrangement before she saw me. My hands were shaking when I switched our identical glasses.

It was instinct, not some brilliant plan. A second later, I realized how dangerous it was. I hurried toward her, but Claire had already lifted the glass to her lips.

“Don’t drink that,” I said.

She swallowed, gave me a strange look, and laughed. “Nervous bride much?”

I went straight to the venue manager, told her what I’d witnessed, and asked her to preserve both glasses and call 911. I wanted my sister stopped. I hadn’t expected her to become her own victim.

Now she was sliding toward the floor.

Ben caught her before her head struck the marble. Our mother, Elaine, pushed through the crowd, her expression changing from alarm to something I recognized instantly.

Fear. Not for Claire. Of what Claire might say.

“She’s just had too much champagne,” Mom announced. “Everyone, please sit down.”

“She had one glass,” I said.

Mom grabbed my wrist hard enough to wrinkle my satin sleeve. “Julia, don’t embarrass this family.”

“Someone put something in that glass. The manager’s called an ambulance.”

Mom’s grip loosened. She looked toward the ballroom doors.

Two paramedics hurried in with their equipment. As they checked Claire, Ben took my hand. His thumb brushed the wedding band he’d placed there only three hours earlier.

“Tell them everything,” he whispered.

I did. I told the paramedics about the packet and the swapped glasses. The manager said she’d secured the drinkware and notified police. Around us, relatives stopped pretending this was ordinary wedding chaos.

Claire’s eyes found mine. She reached for my sleeve.

“The safe,” she slurred. “Don’t let Mom get to the safe.”

I turned.

Mom was gone.

I ran toward the bridal suite, Ben at my heels. The door stood open. Inside, my mother was kneeling in front of the room safe, holding the blue velvet case containing my grandmother’s sapphire necklace.

She stared up at me, pale as my dress.

“You weren’t supposed to be awake,” she said.

I thought the worst thing at my wedding was seeing my sister try to drug me. But the look on my mother’s face told me that glass was only the first part of a plan—and that my grandmother’s necklace had been at the center of it all.

My mother snapped the velvet case shut.

“I was moving it somewhere safer,” she said.

“From a locked safe?” I asked. “While your daughter was being treated by paramedics?”

Ben stepped into the hallway and asked the venue manager to bring security. I stayed in the doorway, blocking my mother’s path. For once, I didn’t apologize for making a scene.

The necklace had belonged to my grandmother, Rose. She’d raised me during the years Mom was busy rescuing Claire from one expensive disaster after another. When Grandma died, she left me her sapphire-and-diamond necklace, with a handwritten note: Wear this when someone finally puts you first.

I’d worn it during our ceremony, then locked it away before dinner. Claire had helped me change and watched me enter the safe code.

“Open the case,” I said.

Mom hesitated. Then she lifted the lid.

The deep-blue stones glittered under the vanity lights. Everything looked perfect, except the clasp. Grandma’s had a tiny engraved rose beside the hinge. This one was smooth.

My throat tightened.

“That’s not her necklace.”

Mom’s expression hardened. “You’re exhausted. You’re imagining things.”

I took a photograph. Two months earlier, an estate jeweler had appraised the necklace for insurance. I still had close-up pictures of the engraving on my phone.

Ben looked between the images. “Julia’s right.”