The Sword of the Silver Knight: A Medieval Fair has come to town, and the Aldens get grandfather's permission to volunteer their time. Benny becomes a page to the Silver Knight, a top suspect when the valuable antique sword used in the fair goes missing.   The Game Store Mystery: When a new store called the Game Spot opens in their town, the Aldens are thrilled. But it's not fun and games when the other stores at Crossroads mall are robbed. What's more, letters are disappearing from the sign in front of the shopping center!   The Mystery of the Orphan Train: The Aldens visit an old Kansas inn that's full of secrets! Nobody knows why a famous photographer visited the inn just to take a single picture. And what about the other legendary guest--a heroic young stranger who'd come west on an "orphan train?"