The Song of Seven book by Tonke Dragt

An exciting new stand-alone adventure by the internationally bestselling author of The Letter for the King. Seven paths, seven unlikely friends, and one extraordinary adventure featuring magicians, secret passages, conspiracies, hidden treasures, a black cat with green eyes and a sealed parchment which predicts the future. At the end of every schoolday, new teacher Mr Van der Steg entertains his pupils with tall tales of incredible events, which he claims really happened to him - involving hungry lions and haunted castles, shipwrecks and desert islands. One day, when he can't think of anything suitably exciting to tell them, he invents a story about a very important letter which he's expecting that evening, with news of a perilous mission. Evening arrives and so, to his surprise, does an enigmatic letter... And so Mr Van der Steg is drawn into a real-life adventure, featuring a grumpy coachman, a sinister uncle, eccentric ancestors, a hidden treasure, an ancient prophecy and Geert-Jan, a young boy who is being kept prisoner in the mysterious House of Stairs. Published By Pushkin Children's Books on 2018-02-06