Stage 8 in the Oxford Reading Tree series marks an important milestone where children transition from simple texts to more complex narratives. At this level, readers are typically 6–7 years old (Year 3 in UK schooling or equivalent), and are developing fluency, inference skills, and greater reading independence

In Viking Adventure, Biff, Chip, and Kipper are whisked away by the Magic Key to the time of the Vikings. They find themselves aboard a Viking longship, where they meet a young Viking boy named Solveig. When a storm forces the crew to land near a village, the children discover that raiders are planning an attack. Working together, they help Solveig and the villagers prepare a clever trap using smoke and mirrors to scare off the invaders. The story ends with the children safely returning home. This exciting time-travel tale introduces young readers to Viking culture and values like bravery, cleverness, and teamwork, all wrapped in a fast-paced narrative with rich illustrations and accessible language.