“So what are you going to do?” I ask.

“First of all, this,” she replies, and in front of my eyes she deletes all her social media accounts. She keeps the screenshots, though, just in case she ever needs them.

“Is that it? What about at school on Monday?”

She smiles, and her hand goes to the small glass bottle she’s been wearing around her neck ever since we got back from Roar. “I’ve got it sorted, Arthur. Mitch taught me a spell and it’s all I need. Oh, and you. If you don’t mind me hanging out with you and Adam Zeng for a while, that would be good.”

I look at the bottle. “Rose,” I say, “what’re you planning to do?”

“I’m going to teach Harriet a lesson.”

“What sort of lesson?”

But Rose refuses to say any more.

Walking to school on Monday feels different. For one thing, Rose hasn’t got her phone in her hand. I’ve hardly seen it since we got back. Instead she’s clutching Mitch’s glass bottle.

“I really wish you’d tell me what’s in there,” I say. “If you’re going to make Harriet disappear in a hurricane or get frozen into a block of ice, I’d like to know about it.”

She looks at me and smiles. “Stop being such a funge, Arthur. It’s just a bit of sea urchin ink mixed with cloudberry juice. Oh, and a dash of paprika.”

“But what does it do?”

“You’ll find out in a minute.”

Rose is speaking calmly, but I know how difficult this is for her. She’s been tense all morning and the only thing that seems to be helping her is the small bottle. As we approach the school gates we see Harriet in her usual spot, leaning against the fence with a group of girls.

They look up when they see us coming. Harriet smiles at one of the other girls and gives her a nudge. Suddenly it’s obvious to me what she’s doing; I can’t believe I didn’t see it before.

“Hi,” Rose says, then she walks straight past them. She’s going so fast that I have to run to catch up with her. Maybe that was it, I think as we walk into school. Maybe all Rose had to do was stand up to Hati Skoll and then her problems with Harriet would fade away!

“Oi, Fish!” Harriet’s voice rings out across the playground, loud and rude.

Rose stops walking. We turn around.