Susie lived in a small yellow house with a blue roof. One sunny afternoon she was playing in the garden together with her cat, Fluffy. She was jumping over puddles and laughing when she suddenly noticed a shiny pebble under the big oak tree. It was purple and shimmered with all the colours of the rainbow. Susie picked up the pebble and felt it tickle her palm. "I wonder what this pebble is?" - she wondered. Then she saw that Fluffy was stuck high up in a tree and couldn't get down! Susie was very concerned, but when she touched the pebble, suddenly.... her hands started to glow! She looked at them in astonishment. "I have a superpower!" - she exclaimed joyfully and waved her hands. Thanks to her extraordinary strength, she gently helped the cat down to the ground. As evening fell, Susie put the pebble in her pocket and decided to see if she would discover more superpowers. But then, a strange shadow appeared behind the tree, moving very slowly and getting closer....