normal Tuesday when my 11-year-old daughter, Ivy, opened her new library book and a folded piece of paper fluttered onto her plate. She had just checked out ‘Charlotte’s Web’ from the Maple Street Library, a quiet little brick building a few blocks from our house where she practically lives after school.

I thought it was just a forgotten bookmark. We always find old receipts, index cards, or grocery lists tucked into library books. But then Ivy unfolded the crisp, white square of paper and started reading out loud. “Mama, listen to this,” she said, chewing on a bite of spaghetti.

“It says, ‘To the girl who always picks this book: I shelved it for you today. I watched you read it in the corner chair. You bit your thumbnail. Your father does the same thing.'” The sound of my fork hitting my ceramic plate echoed through the suddenly quiet kitchen.

My husband, Mark, stopped pouring his water and stared at me. My stomach had completely dropped into my shoes, a cold sweat breaking out across the back of my neck. Ivy is adopted. We brought her home when she was just four days old. It was a strictly closed adoption facilitated by an agency two states over.

The agreement was ironclad: no contact, no shared names, no medical history updates unless it was life-threatening, and absolutely no way for anyone from her past to track us down. We wanted to protect her, and we wanted to protect our family. But Ivy just kept reading the note, completely unaware of the absolute panic rising in my chest or the terrified look Mark and I were exchanging.

“There’s more,” she said, her bright green eyes scanning the rest of the page. “It says, ‘You look just like him. He doesn’t know you exist.

He sits in the same chair on Tuesdays.'” I reached across the table and snatched the paper from her hands a little faster than I meant to.

Ivy blinked at me, startled by my sudden movement. “Hey, I wasn’t done,” she protested, but I couldn’t even form the words to apologize. I stared down at the paper. The handwriting was incredibly small and careful, written in a distinct purple ink that looked like it belonged on a wedding invitation, not a creepy library note.

I read the words again, my heart hammering against my ribs. He sits in the same chair on Tuesdays. Who was “he”? Her biological father? And who was writing this? But it was the bottom right corner of the page that made me feel like all the oxygen had been sucked out of the room.

Down at the bottom, in tiny, meticulous script, it said: Letter 37. Thirty-seven. Someone had been watching my daughter. Someone who knew her most intimate history, and they had left thirty-six other letters before this one. “Honey, why don’t you go wash up and pick out a movie for us?” Mark said, his voice tight but surprisingly steady.