ONCE PENNY’S illness had a name, the depth of its roots became suddenly and irrevocably visible. It wasn’t just now with Ava, it was always with everything. It was a lifetime of inexplicable illnesses and injuries, a draw to the sick that masqueraded as compassion, a vast knowledge and infinite obsession with medical details that far exceeded professional usefulness. It was the ghosts of the two little girls who had never been, who lingered now like bad omens, two tiny Cassandras.

Having a name for Penny’s affliction brought scant relief as the treatment possibilities were vague and the outcomes bleak. Most of the cases I read about in my frantic Googling of the disease made headlines because the children in question had died. There seemed to be no stories of people triumphing over the disease to be found anywhere, no kernel of hope to hold on to. Even the notion that Munchausen syndrome by proxy was a treatable disease at all was up for debate; afflicted women were child abusers and monsters, rather than victims themselves suffering from their own dark delusions. We didn’t want Penny punished, we wanted her helped. We wanted her to be protected from herself and Ava to be protected from her.

The only way I could think of the disease was as something entirely separate from my sister, as though it were a parasite that—if we could somehow remove it—she would recover from. Even though I could see now how far the tentacles reached into Penny’s past, my conviction remained that there was still a Penny in there to be saved: the Penny I’d known as a girl, and even as a teenager, the one who was sweet and sensitive and silly. I had so many memories of her laughing and gossiping with Emily, going bonkers over some boy, or prattling on in their shared made-up language—a conflagration of gibberish and the first-year German they’d taken together their freshman year. It occurred to me that I hadn’t seen her really laugh in what felt like years. But surely there was a way to bring her back.

Penny called me about my mother’s betrayal nearly as soon she discovered it. I was back in the Park City condo then with Luke and Blair had come for dinner; thankfully, it was only the three of us. I took the phone call in the bedroom.

“Katie, Mom is crazy, can you believe her? She called the doctors and told them all these lies about me! What the hell?” Penny was sobbing. The two days since CPS had come had been like a car accident happening in slow motion, the severity of what was taking place deepening by the second. Ava had been returned to her parents quickly, with a court order that required they stay with Penny’s bewildered in-laws under strict supervision.