The final day of my visit was a sunny one, and Penny and I took a long walk along the lakeshore, Ava bundled up to protect her from the bracing air. She was livelier that day and when Penny and I stopped to rest for a while on a bench, she squirmed ferociously in my sister’s lap, making us both laugh as she reached for and burbled at the geese who strutted along nearby. The moment of normalcy was like a sliver of light. Maybe everything would be okay.

On the way home, I stopped by the grocery store to pick up protein bars and tried my mom’s cell to see if she needed anything. She didn’t answer. I tried my dad. Nothing.

But when I arrived home, both cars were there. In the middle of the day.

“Mom? Dad?” I called through the foyer. “Hi, buddy,” I said, leaning down to scratch Barry’s ears.

“In here, Katie.”

I came down the hallway and was greeted with the strange sight of my mom and dad sitting side by side at the ancient dining set. I noticed with alarm that my father’s eyes were red-rimmed.

“Hi, honey,” my mom said. “Can you sit with us for a minute? We need to talk to you about Penny.”

I lowered myself numbly into the chair next to my mom and could feel the dam I’d been patching over for months—years—to forestall this very moment finally bursting. I felt tears springing to my eyes, my breath quickening. That afternoon while I’d walked with Penny and Ava in the park, my parents had been to see Doctor Anderson, our family practitioner of over two decades. They’d laid out for the kind doctor all of the many moments that I’d been trying for years to convince myself were isolated incidents, the products of growing pains and bad boyfriends. Taken together, they added up to a horrible, unspeakable truth. Penny wasn’t simply unlucky, she wasn’t just a worrier or a hypochondriac. She likely suffered from a mysterious disorder known as Munchausen syndrome by proxy, a grotesque and terrifying disorder that had been a subplot in a popular late 1990s horror film. Her unfortunate health history hadn’t been some bizarre curse; it had been her creation. And when Ava was born, her focus had shifted to the baby. There wasn’t a great deal known about the disorder, but Penny fit the profile: female, white, middle class, with a job in the medical profession.

“What the hell are we going to do?” I asked my parents. Without realizing it, I’d clasped my mother’s hand and was squeezing it so hard my knuckles had gone white.

“We’ll get her help,” my dad said, trying to sound certain. “We’ll stick together. We’ll get through it.”