She bows her head. “It took us a long while to come to terms with Alice’s death.” Her voice is low and flat. I watch her throat move as she swallows, my eyes traveling from the sharp blades of her collarbones to the blood-red beads that spill down the front of her black dress.

“I left home about a year after you and your parents moved away. Trained as a nurse. I only joined the practice a little while ago. I had no idea you were…”

Something inside me gives way. The new practice nurse. The one Ross keeps referring to. The one who went with him to visit a patient the other night, who ate chicken and chips with him while I waited at home, wondering where the hell he was. It’s Catherine Dawson. What kind of freakish coincidence is this? What kind of headfuck?

Slowly, I move toward the leather chair and sit down, my hands gripping the armrests. It’s the first time I’ve allowed my eyes to linger on her face since that first shock of recognition in the hall. Apart from a few lines around the mouth, she looks exactly the same as I remember her. Alice is there, too. In her eyes, her jawline, her coloring. Is this what she might have looked like, if she’d had the chance to grow up?

“I acted badly for a while,” she says. “I’m sorry for that, Lizzie, but I was grieving. My little sister was dead and…” She takes a second to control her breath. “I just wanted to know how my baby sister died. Why she died. I couldn’t accept the fact that we’d never know.”

I swallow, nervously. None of this is real. It can’t be. Catherine Dawson turning up at our party. Catherine Dawson working with Ross, eating takeaways with him. How is that possible?

“Lizzie? Are you all right?” Her voice is gentle, concerned. The sort of voice a counselor might use. But of course, she’s a nurse now, a professional. It’s been twelve years since Alice died.

The silence between us lengthens.

“I’m not trying to give you excuses,” she says at last. “I’m just trying to explain what it was like.” She’s staring directly at me now, an imploring look in her eyes.

I turn away. I don’t want to feel sorry for her, but somewhere in the back of my mind I know I’m recalibrating my emotional response, that, despite everything, a part of me is already trying to understand.

She stands up. “I’ll leave. I’m ruining your party.”

“No. Stay and have a drink with your colleagues.”