Creeping Shadow (The Rise of Isaac, Book One) by Caroline Peckham

its decaying mouth. “Couldn't save your mother...won't save your sister.”
    If he rang the bell he would never be able to help May. The thought filled him with a slither of courage, just enough to make his hand snap back towards him and release the rope.
    He turned towards the figure, preparing to face it.
     

7
    Beyond
     
    A grinding of stone sounded and a warm glow split the darkness in half.
    Oliver rushed towards it with a wave of relief that spread through his entire body as he left the apparition behind. He sighed heavily as he found himself back in the underground chamber with his sister and Ely.
    "Congratulations. You've both successfully completed the challenge," Ely said, grinning broadly.
    "That was horrible," May said, running her hands up her arms.
    "What happened to you?" Oliver asked, glancing back at the door as if the grotesque figure of his father might still be lurking there.
    May grimaced. "It was like everything I'm afraid of was living in this awful maze."
    Oliver nodded, subtly stepping away from the door behind him. "What did you see?"
    "When I went in the walls closed behind me and I thought the best thing to do was to stay put. But then this guy appeared, he was huge and his face was just this hollow, black space and I tried to run from him but he grabbed my wrist and dragged me through the maze."
    Her voice shook as she spoke and Ely looked at her with pity in his eyes as she continued. "He took me to this podium in the centre of the maze and I was strung up in front all these people, all with the same indistinct faces but their eyes were visible and they were just staring at me, waiting for me to speak or do something and I felt so vulnerable. I wanted to ring the bell, I almost did-" she cut off, her breath catching in her throat.
    Oliver stepped forwards and hugged her firmly then she buried her face in his shoulder.
    "I'm sorry," Ely said. "This Gateway challenge is testing and quite cruel. But you both did so well, do you have any idea how many people ring a bell and fail this test?"
    Oliver stepped away from May and nodded. "We had to get through it. Now we can visit your friend who can help May."
    Ely smiled brightly. "Yes. Now, I've got something for you both." He rummaged inside his jacket and retrieved two familiar objects that Oliver recognised from the attic.
    Oliver glanced at May in surprise as they each took the heptagonal pendant inscribed with their name.
    "They're called Locks. I made them for you years ago. I know your mother never wanted you to know about the worlds but I hoped one day she might change her mind." He winked at them.
    Ely strolled over to the Gateway and plucked four, sparkling gems from it before returning to them. Oliver placed the Lock around his neck and May imitated him.
    "You can only gain access to each world by possessing a key," Ely said.
    "Key?" Oliver asked curiously.
    "The keys," Ely held up one of the twinkling jewels from the Gateway. "They're mined for by gem trolls in Glacio." He rubbed the tiny sphere between his fingers.
    Oliver looked closer at the translucent key in Ely's hand and suddenly recognised it. He retrieved the ball he had carried in his pocket ever since discovering it in the attic. It was identical.
    "Where did you get that?" Ely looked stern.
    Oliver realised his mistake. "I found it in the attic," he admitted.
    "Oh, so you went exploring, did you?" Ely asked, shaking his head. "You're just like your mother." He softened and broke into a smile. "Well here you are," he said, handing them two each. "The Locks are designed to hold them."
    Oliver took the tiny spheres in his hand, cupping them in the crease of his palm where they sat, twinkling up at him.
    "Can't I use the one I found?" he asked.
    "I'm afraid not. The gems must be taken from the Gateways and encoded within a brief amount of time, otherwise they become useless."
    "Why?" May asked.
    "The gems feed off of the Gateway, it's where they acquire their magic. The Gateways