My twin sister vanished in the sunflower sweater our mom knitted the night we turned 16 — 40 years later my granddaughter wore it home and said the woman who cleans her school had handed it to her.

The envelope was light. One page, maybe two.

I sat in the Ridgeline parking lot with the engine off and the heater still ticking as it cooled, and I opened it.

Her handwriting wasn't what I expected. For forty years I'd been holding on to those big looping teenage letters. This was small and careful. The handwriting of a woman who'd learned to take up less room.

*Dear Nora,*

*If you're reading this, Marta kept her promise. I always knew she would. She's the best thing I ever made.*

*I've started this letter a hundred times and thrown away every version. So I'm just going to say it plain, because I don't have a lot of time left and I don't want to spend it hunting for pretty words.*

*I did not run away. I need you to know that before anything else. I know that's what everyone thought. It wasn't true.*

*Dad found my notebook. He came up to our room that night while everybody was at the table. I heard him on the stairs and I knew. I went down to the yard and he was already out there waiting.*

*He wasn't even angry. That was the worst part. He was calm. He told me what would happen if I stayed — what he'd tell the police, that he had my handwriting on papers already, that people would believe it. A teenage girl, run of the house, holding a grudge. He made it sound so reasonable.*

*And I believed him. I was sixteen and he was my father and I believed him.*

*I kissed Mom. I stole the frosting. I said save me a piece because I thought if I said something normal it wouldn't feel like goodbye. I thought maybe it wasn't really goodbye. I thought I'd find my way back.*

*I never found the way back.*

*I want to tell you about my life, but I don't want this letter to run too long, because I know you'll cry and I don't want you crying over it for too long. I was okay, Nora. I need you to hear that. I had a life. I had Marta. I had a little apartment with a lemon tree outside the window and a neighbor who taught me to make soup and work I was good at, and hard years and then some easier ones.*

*I thought about you every birthday. Every single one.*

*I thought about Mom. I picked up the phone so many times. I was scared. I was ashamed, even though I know now I had nothing to be ashamed of. By the time I understood that, so many years had gone by that I couldn't figure out how to reach back across them.*

*I'm sorry I didn't find a way. I'm sorry I turned around at that airport. I'm sorry Mom died not knowing. That's the one I carry heaviest.*

*Tell Marta she did everything right. Tell her I said so.*

*And Nora — please don't spend whatever years you've got left being angry for my sake. I was angry a long time and it never gave me one thing back. What I want for you is what I finally found at the end. The ordinary days. The soup. The lemon tree. The neighbor who shows up when you need her.*

*I love you. I always did. You were the other half of the birthday.*

*Diane*