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

which was destined to wash away the snow. He was haunted by strange dreams, making him toss and turn in a hot sweat.
    He looked down to find the strange, heptagonal pendant in his hand. His name blazed on the back of it, glaringly bright.
    "Oliver?" A familiar, female voice spoke.
    He looked up and saw his mum. A hazy, golden light emitted from the pendant, illuminating her form but barely penetrating the darkness surrounding her.
    "Mum? Where are you? Please come back."
    She looked sad and lost then she vanished and the scene changed. His hand was still outstretched but the pendant was gone. Someone took hold of it and pulled him forward. He could see the back of a large figure, a man, dragging him toward a bright, blue sphere of light.
    "No, stop," Oliver said, tugging his arm back as fear invaded his chest.
    The man turned to him but his face was indistinct, hidden by shadow. "Come with me son."
    "Dad?" Oliver said and a sense of hope grew inside him. "I thought you were dead."
    "I am dead," he said and his face became clear. It was a bloodied skull but the eyes were intact, gazing at him out of boney sockets. Sinews dangled from the bone.
    Oliver gasped and tried to tug his arm away once more but the skeleton dragged him on towards the light.
    "No-"
    A scream ripped through Oliver's dream and he awoke with a violent jerk. It sounded again and a chill engulfed him as he realised it was May.
    In a panic, he ran flat-out to her room and flung the door open.
    Oliver fumbled for the light switch, squinting into the darkness as he desperately tried to find it. He cursed as he gave up and hurried into the room, his eyes adjusting slightly and focusing on a solitary figure on the floor.
    May was curled up in a ball, squirming and writhing. She let out another, shuddering scream and Oliver threw himself to her side, rolling her over to try and stop her body from spasming.
    Panic set in and he shouted for Ely.
    It seemed as though an age passed before Ely appeared in the doorway though Oliver knew it couldn't have been more than a minute.
    "What's going on? I can't see a thing," Ely said, sounding frustrated.
    The overhead light came on and the blood drained from Ely's face as he spotted May. He leapt to her side, suddenly a man in control. A look of concentration crossed his features as he examined her carefully.
    May's eyes were open but they roamed unseeing, bloodshot and red. What scared Oliver more were the dark bruises that covered her body and the thick, black veins that slithered like snakes between them under her skin.
    The marks weren't like anything Oliver had ever seen, they swirled and pulsed as if they were alive. Those that ran down her neck were larger and darker than the others and led towards the worst mark, sitting just above her heart.
    "What's wrong with her?" Oliver asked frantically.
    Ely shooed him away and continued examining his sister.
    May gasped suddenly as the black veins reached up towards her temples.
    " Help her ." Oliver clasped May's face as if he could stop the veins himself. He felt helpless and lost as he gazed at her, his world collapsing around him.
    "I've never seen anything like this. I may be able to harness the curse temporarily..." Ely trailed off and continued to mutter to himself under his breath.
    Oliver couldn't make out the words.
    "Curse? What do you mean? She's sick. We need to get her to a hospital." Oliver stood up, meaning to find a phone, his brain finally clicking into gear.
    Ely grasped his arm tightly and pulled him back to his knees.
    "You need to listen sharp, Oliver. I'm only going say this once and it's going to sound all shades of crazy, but you better trust me because I'm the only chance she's got. Got it?"
    Oliver nodded, stunned.
    "There's no doctor in this world who can cure May from this-"
    "But-" Oliver cut in.
    "No buts. You listen to me. No doctor in this world can help her, Oliver. But there are other worlds. And that's where this curse can be healed. I know