Karen, Sally and Alex are three teenagers who take a camping trip at Yellowstone National Park during a wolf alert. Two of the park’s wolves are missing and the three teens decide to look for them. Their trip becomes an exciting, yet dangerous adventure when they meet a hungry grizzly bear, an angry mountain lion and a herd of bison that destroy their tent. Will they ever solve the mystery of the missing wolves?

Green Apple by Black Cat is a collection of graded English readers created for students aged 7 to 14, with levels ranging from A1 to A2/B1 of the CEFR. It includes adaptations of literary classics, original stories, and non-fiction, featuring engaging illustrations and activities to develop all four language skills. All titles come with full audio, and many are available in eReader format with interactive activities. Green Apple is ideal for learners looking for an enjoyable and effective way to improve their English while reading engaging and enriching content.