Jess unpeels her thighs and scrambles to her feet, tiptoeing silently into her bedroom, not daring to close the door for fear that the sound of it scraping against the carpet will betray her. She slips back onto the chair at her desk and resolves to stay there until her parents get home.

Three days later, Jess is walking down the stairs to the basement kitchen when she is stopped by the sound of crying.

It is a quarter to seven on Sunday morning and she has woken earlier than usual, hunger growling in her stomach. She had assumed everyone else in the house would still be asleep, but there are three voices coming from the kitchen and Jess sits silently on the top stair, listening.

“It’s not fair, Mum. Why is this happening to Zoe? Why can’t it happen to someone else instead of her? It’s just not fair.”

Lily is crying: loud, convulsive sobs that make the hairs on Jess’s arms stand on end.

“I know how hard this is, sweetheart. I know it’s . . . horrific.”

Her mum’s voice wavers but Jess can tell she is trying to make herself sound calm.

“We just have to be strong for her, Lily. We just have to make sure she knows we love her and we’re here for her.”

Her dad is speaking now and for a few lonely seconds, Jess feels left out, as though the grown-ups and Lily are deliberately excluding her from a conversation she ought to be a part of. She imagines the three of them creeping down the stairs so as not to wake her or Zoe, imagines them having planned this secret rendezvous down in the farthest reaches of the house where they are unlikely to be heard.

“But she’s in so much pain. It’s horrible. No one should have to be in that much pain. I hate seeing her like this. We can’t just sit by and watch her suffer and do nothing.”

Lily is sobbing and Jess feels a frown pucker her forehead. It is news to her that Zoe is in pain. She has known, since Zoe came home from the hospital three days ago, that her sister is very tired and needs lots of rest. She knows that she needs to be quiet so as not to disturb her, has perfected the art of tiptoeing up the stairs and across the landing as silently as a mouse. But no one has told her that Zoe is in pain. And the revelation makes her feel cold inside, as though someone has packed ice cubes around her heart.

“I’m sorry, Mum. I’m sorry for all those times I was jealous. I didn’t mean it. I didn’t mean any of it.”

“Shh, stop that. You’re a lovely sister to Zoe, to both of them. I know it’s always been difficult, that you’ve always felt a bit left out, but you mustn’t start thinking like that.”

Jess rubs her fingers over the bridge of her nose. There is too much new information fighting for space in her head and it is beginning to ache.