Junior Agent Jack and the Coronation Chaos

When Jack's teacher, Mr Brown, cannot escape an enemy agent disguised as an Ofsted Inspector, he gives Jack a mystery envelope to take out of school. However, since Jack's father died, he has focused on keeping himself and his remaining family safe, so the last thing he needs is an adventure. But that is exactly what he gets. The mysterious envelope leads Jack into the biggest adventure of his life. Can he and his friend, Tess, return the envelope, can they rescue Mr Brown and can they save the King from the perils plotted for his Coronation?