Book 2 Warning: This book contains an epic adventure that places three fourth graders in extreme danger. Hiro, Bryan, and Zahra are officially Senshi Warriors hiding in plain sight as fourth graders. It's up to them and their friends to save the world using their wits, creativity, and an alien-enhanced backpack. But why is Bryan acting so strangely, and why are pickles so important to the human race? Our heroes may not have all the answers, but they do have each other.