I came home smiling to surprise my parents, then found them motionless on the floor and learned someone had poisoned their food.

I showed up at Kara’s apartment at 7 a.m. the next day, pounding on the door so loud the old lady from 2B stuck her head out into the hall and yelled at me to “keep it down, some of us are trying to sleep off a migraine.” Kara opened the door 10 seconds later, her hair a mess, wearing Tyler’s old Ohio State hoodie, her eyes puffy like she’d been crying all night.
“Em?” she said, blinking. “What’s wrong? Is it Mom and Dad? Did something happen —”

“Where is he, Kara?” I cut her off, pushing past her into the living room. Empty beer cans littered the coffee table. A half-eaten pizza sat on the counter, crusts hard as rocks. “Where’s Tyler?”

Kara’s face went white. “He’s at work. Why? Emily, you’re scaring me. What’s going on?”

I pulled out my laptop, pulled up the night footage of Marnie and Tyler, and spun it around to face her. She stared at the screen for 10 seconds, then sank onto the couch, her hands flying to her mouth.

“No,” she whispered. “That’s not… he told me he was out with his friends that night. He said he was at the bar.”

“When was the last time you talked to him?” I said, sitting down next to her. “Kara, look at me. The police are looking for Aunt Marnie. They think she poisoned Mom and Dad. And Tyler was with her. He took money from her. What do you know?”

Kara broke down sobbing then, her whole body shaking. I held her while she cried, my own tears mixing with hers, and when she finally calmed down enough to talk, the story she told me made my blood run cold.

Tyler had lost his job at the auto shop 3 months before, she said. He’d been too ashamed to tell anyone, so he’d been leaving the house every morning like he was going to work, then driving around town or sitting in the parking lot of the Walmart until it was time to come home. He’d blown through their savings on scratch-offs and poker games with his cousins, and when the rent was 2 weeks late, he’d started borrowing money from “a guy he knew.” Then the guy had come after him, threatened to break his legs if he didn’t pay back $15,000 in 2 weeks.

“He was desperate,” Kara said, wiping her nose on her sleeve. “I told him we’d ask Mom and Dad for a loan, you know? They’d help us. They’d never let anything happen to us. But he said no. Said Dad would judge him, say he was a loser, that he’d never be good enough for me. Then… then Aunt Marnie showed up at our apartment. Out of nowhere. She said she’d give Tyler the money to pay off his debt if he did her a ‘small favor.’”

“What favor?” I said, my voice cold.

Kara hesitated. “She said she needed him to copy Mom and Dad’s house key. Said she wanted to get some of Grandma’s old things from the attic that Dad had ‘locked away.’ She said she’d be in and out, no one would ever know. I told him not to do it, Em. I swear I did. But he was so scared of those guys… he said it was the only way.”

“Did she tell him she was going to poison them?” I said.

Kara’s eyes went wide. “No! God, no. He had no idea. He told me she just wanted old photos and jewelry. When we found out what happened… he was sick. He said he’d never have helped her if he knew she’d hurt them. He was going to go to the police yesterday, but then he got scared they’d arrest him too, so he ran. He left last night. Said he was going to go find Marnie and make her confess.”

I didn’t know what to believe. Tyler had always been a little rough around the edges, but he’d loved Kara since they were 16. He’d been the one who stayed up with her when our grandma died, who’d helped Dad fix the porch last summer, who’d taught Lily how to ride a bike without training wheels. Could he really have been that desperate?

The police called an hour later. They’d found Marnie at a cheap motel on the edge of town, hiding out under a fake name. They’d arrested her, and she was already at the station, asking for a lawyer. I told them about Tyler, about the money, about the key, and they said they’d put out a warrant for his arrest too.

Michael picked me up from Kara’s a little while later, and we drove out to my parents’ house to look for any more clues — the police had finished processing it a few days before, said we could go back to get whatever we needed. The house still smelled like stale air and regret, and I had to stop in the living room for a minute, staring at the spot where I’d found Mom and Dad, before I could keep going.

We were up in the attic, looking through Grandma’s old boxes, when Michael found it — a thick manila envelope tucked behind a stack of my old yearbooks, labeled “PRIVATE — FOR EYES ONLY” in Dad’s messy handwriting. He opened it, and his face went so pale I thought he was going to pass out.

“Em,” he said, handing me a piece of paper. “You need to see this.”

It was a paternity test. Dated 18 years before. The results were typed in black and white, no room for doubt:

PROBABILITY OF PATERNITY: 0.00%.

The child listed on the form? Kara Marie Carter.

My little sister. The girl we’d grown up with, fought with, shared a room with for 10 years. Dad wasn’t her real father.

I looked at Michael, and for the second time in 24 hours, I felt the ground drop out from under me. We’d spent the whole day chasing Aunt Marnie and Tyler, convinced they were the bad guys. But what if Kara had a secret of her own? What if she’d found out about the test — and decided to get revenge on the parents who’d lied to her her whole life?