Victor Appelton 
Tom Swift and his Chest of Secrets 

Tom constructs a large, heavy brass-bound oak chest to hold his blueprints, formulae, and models until an underground vault can be built. But Tom is attacked and his possessions—including the chest—are suddenly missing, along with hie friend Koku. Tom must discover who stole his Chest of Secrets and save Koku from the villains…if he can!