She insisted that my mother must have given the card to a friend or a distant relative before she died, asking them to deliver it on Maya’s first birthday. It made sense. It was exactly the kind of thoughtful, meticulously planned thing my mother would do.

We framed the card, thanking whatever guardian angel had delivered it, and considered the mystery solved. But then Maya turned two. And another plain white envelope appeared. Same crisp twenty-dollar bill. Same blue ink. Happy Birthday, sweet girl. Maya turned three. The card appeared again.

Maya turned four, five, and six. By Maya’s seventh birthday, the tradition had shifted from a heartwarming surprise to a deeply unsettling puzzle. Emily stopped trying to rationalize it. She began to think it was a cruel prank, someone who had somehow gotten hold of my mother’s old letters and was copying her handwriting.

But I knew better. You don’t just mimic the soul of someone’s penmanship. The flow, the microscopic imperfections, the way the ink pooled slightly at the end of the word ‘girl’—it was my mother’s hand. I knew it the way I knew her voice. Every year, I drove myself crazy trying to figure out how they were getting into the mailbox.

Our house sits at the end of a quiet cul-de-sac. The mail carrier usually arrives around noon, but these envelopes were always there first thing in the morning. I started having trouble sleeping in the days leading up to Maya’s birthday. I would stare at the ceiling, wondering if a ghost was walking up my driveway in the dead of night.

This past March, as Maya’s twelfth birthday approached, I reached my breaking point. I couldn’t take the mystery anymore. I needed to know who was playing this beautiful, agonizing trick on us. On the morning of Maya’s birthday, I woke up at 4:30 a.m. I poured black coffee into a thermos, bundled up in my heaviest coat, and quietly slipped out the back door.

I walked a block down the street and climbed into my sedan, parking it in a spot where I had a clear, unobstructed view of our mailbox. It was a freezing, miserable morning. The damp cold seeped through the floorboards of the car. By 6:30 a.m., my windows were fogging up, and I was shivering so violently I kept spilling my coffee.

I started to feel ridiculous. I was a sixty-year-old woman staking out her own driveway like a private investigator. I told myself I would wait until 7:30, and then I was going back inside to warm up. At exactly 7:15 a.m., movement caught my eye.

It wasn’t a car, and it wasn’t a mail carrier. Walking briskly down the sidewalk was a young woman. She looked to be in her late twenties, wearing a heavy gray wool coat and a dark beanie. She kept her head down against the biting wind.