Oliver peered up. The slide was so long he couldnt see the top. The sides were completely smooth, with not a single ridge to use as a foothold. Climbing it would be impossible.

Now what? Esther whispered.

It was their only way out of the school. Oliver realized that hed have to use his powers.

I have an idea, he told her.

Oliver closed his eyes to help calm his mind. He summoned his powers then visualized his hands turning into suckers. As he unfocused his grip on reality, he forced the new image out in its place. When he looked down, his hands had indeed transformed.

Esther blinked with shock. What are those?

Suckers, Oliver said, waving them. For climbing.

Are you expecting me to hold on? Esther asked, an eyebrow raised.

Got any better ideas? Oliver countered.

Esther sighed with reluctant acceptance. She jumped up on Olivers back, clinging tightly to him. Oliver began to climb up the inside of the slide.

It was hard going, both physically on his limbs and mentally holding onto the reality of his suckered hands. It was made even harder going by the extra weight of Esther. She was gripping on so tightly around his neck that it was making it difficult for him to breathe.

Esther, he croaked. Youre strangling me.

Sorry, she said, barely loosening her hold.

Oliver climbed on.

A moment later, Esther whispered in his ear. I hope you know this doesnt count as our second date.

Oliver felt his lips twitch at the side. No. Well go on a real one when I get back.

They both fell into tense silence. There was no guarantee Oliver would ever make it back.

At last they reached the top of the slide. They clambered out, emerging into the narrow corridor. Oliver remembered following Ralph along it on his arrival at the school and felt a pang of grief for his absent friend. At least he had Esther by his side. For now, anyway.

They headed along on hands and knees until the ceiling was high enough for them to stand. Then they hurried along the corridors, following the winding paths to the main door.

They halted. This was where Professor Amethysts invisible wall was.

Oliver reached out and touched its surface. It felt like a bubble, like elastic resisting him. He pushed and felt it push back. Just as he suspected, it was impenetrable. He looked over at Esther.

She was gazing at the empty space. She reached forward with her fingertips and caressed the air.

It feels just like one of mine, she said.

Do you think its made the same way? he asked. Through waves?

Esther nodded. I do.

How will I get through? Oliver lamented.

I think I might be able to make an opening, Esther said. Using my own specialism to counter it.

Olivers eyes widened. And you thought sonar was the worst?

Esther smiled coyly.