The adventure of the charge of the old brigade

"When a child is snatched, the Baker Street irregulars are quickly on the trail of the kidnap gang. They are soon caught up in a hunt for buried war-time treasure - but who is behind all these events? The Irregulars put a plan into action that ends in a race across London to stop the kidnappers, where they also discover the identity of 'M'"--Back cover. Suggested level: primary, intermediate.