A text message from my best friend, Val, woke me up way too early on Halloween morning: "What were you doing in the river a few minutes ago, and where are you now??"

My reply: "Are you on drugs? I'm in bed (confused face emoji)."

Two seconds later, the phone rang. "OK, this calls for real-time discussion," Val said, her voice interrupted by huffs and puffs. "Chelsea, I was at cross country practice, and I saw you wading into the river. Then poof—you were gone. And you texted to say you didn't want me to pick you up for the party tonight and you told me to leave you alone until tomorrow."

"Seriously?" This had Halloween prank written all over it. But the strange thing was, I couldn't figure out who would take the time and make the effort to trick Val and me. We weren't in the popular or unpopular crowd. We were basically the ones no one noticed.

"I guess you didn't send the message?" Val asked as if she really, really wished I did.

"Nope." Before Val could dream up a bazillion crazy scenarios for what was going on, I cut her short. Someone had played a stupid joke on us, and that was that.

As I hung up, the scent of pancakes found its way under my door and to my nose. Mom was awake and cooking. And then I glanced at the clock. It was later than I thought. I sprang out of bed, jumped into the shower, and turned on the water full blast. If I didn't get moving, I'd be late delivering the chocolate-peanut butter swirly spice bars I'd made for the youth literacy charity's annual "Spookfest."

But when I got to the fridge, they were gone. There was no way two hundred dessert bars could be hiding behind the leftover pizza or the gallon of milk. Still, I hunted around for a while until Mom told me to shut the door—I was wasting energy. I didn't want to bother her about them, because, well, Halloween was a tough day for us. I couldn't dwell on that right now though. I had to get to the Spookfest people. And fast. I had explaining to do.

When I burst through the doors of the recreation center, Gerry the Jolly Jack-o'-Lantern, who actually was Gerry Johnson—the event's organizer—pulled off her mask and stared at me as if I had two heads.

"What are you doing back here?"

"Back here?"

Then my eyes settled on the table behind Gerry. My chocolate-peanut butter bars took up most of the space.

"You delivered tons an hour ago, Chelsea."

"Wait a minute. I didn't bring those."

"Yes you did," a guy I didn't recognize said, giving me the once-over. "Only difference is you were wearing an orange dress. And now you're in sweatpants."

The words "orange dress" did it. A major shiver shot up my spine. My blood didn't run cold—it turned to ice. My hands loosened their grip on the chair I'd grabbed to steady myself, and it crashed to the ground. But I didn't care. The only thing I could think about was her. The girl who wore an orange dress and used to pass for me all the time. The girl Val saw near the river.

"Are you OK?" Gerry asked.

No one would believe what was going on—except Val with her wild imagination.

I had to keep my cool. I forced a big fat fake smile onto my face, wished Gerry a spooky Spookfest, and took off running.

The wind had picked up, and it howled in my ears and swirled into the darkening sky. I could almost hear her voice in it, that girl who looked like me. Tears flooded my eyes. No, Chelsea. Stop. Do not think about it until you get to Val's place.

I collapsed against her front door, then rang. Somehow, I managed to look relaxed and normal. I even chatted with Val's mom until Val and I were out of there and on our way to our usual coffee shop down the street.

We didn't say a word until we sat pouring extra sugar into our caramel-apple-mocha coffees.

"I know this sounds nuts, but... I... I have to say it." My voice trembled. Val did her famous eyebrow-raise, and I could tell she was holding her breath.

My words came out in a jumble. "I had a twin sister. Margo. She died two years ago, right on Halloween. Drowned in the lake by our house. Before we moved here to Boston."

She'd worn an orange dress that day. My dress.

"Oh my God. I'm sorry." Val's hand flew to her mouth, then she reached across the table to squeeze my arm. She didn't immediately see what was happening here, didn't make the connection. Well, who would? Margo reappearing two years after she died—that was something you'd see on Netflix. Not in real life.

I opened my mouth, ready to tell Val that the girl she'd seen was actually my sister. And she was a ghost. But Val beat me to it.

"It's her, isn't it? She's the one I saw in the river."

"You believe this?" My eyes turned into saucers at Val's nonchalance.

"Well, yeah." She shrugged. "The evidence points to one thing, or in this case, to one person."

"And there's more," I hissed, quickly telling her about how Margo delivered my chocolate-peanut butter bars to Spookfest.

I lowered my voice to a whisper. "The thing I don't get is, if ghosts do exist, why did Margo come back today? She died on Halloween, sure, but she didn't come back last Halloween. It doesn't make sense."

"Hmm." Val looked thoughtful for a second. "Maybe she's just hanging out."

"Or she's being her silly goof-off self, playing tricks to freak me out." I tried to sound flippant as we both got up and dumped out the rest of our coffees, but fresh tears prickled in the corners of my eyes.

Val slung her arm around my shoulders, and we walked out into the night.

And then it was later, and we were dressed as 1980s girls, rubber bracelets stacked up our arms and fluorescent tops under our coats. The wind had more than picked up. Val drove us an hour to Salem, to the old mansion where my big crush, Noah, was throwing a party. A wave of party-goers disappeared into open doors as Val parked, then we stepped into the wild wind that pretty much lifted us off the ground. We fought against it, half-laughing, half-terrified of nature's fury.

Val pushed ahead and made it inside. And then something warm and much more powerful than a gust hurled me to the side, forcing me to the ground. A second later, a massive old lantern fell, impaling the spot that would have been my head.

Screams echoed in my ears. Val, Noah, everyone rushed toward me, crowded around as if I were a miraculous being. Like I'd walked on water or something. Noah as a vampire stretched his hand out to me, but I couldn't blush or go all giddy. I couldn't focus on anything except the heavy steel and shards of glass.

"Are you OK?" the blend of squealing voices repeated over and over. And I nodded over and over.

My eyes wouldn't leave the site of the accident. Because something had caught their attention. I stepped forward, reached into the mass of destruction, and pulled out a wisp of orange fabric. The fabric of that orange dress.

"Margo." Her name was a whisper, whipped away by the wind. And now I understood why she'd come back to me this Halloween.