Pythagoras appeared in the doorway. “Come, children. Come in and let's have our first lesson together,” he said in a friendly voice, opening the door wide and looking for all the world like a benevolent grandfather. He turned on his heel and preceded them into the classroom.
Muko put out a hand and grabbed hold of his three
friends.
“Hey,” he whispered as they turned to look at him in surprise. “I know who this guy is. He's mad, and a murderer. I remember all about him! We might be in real danger.”
“So what do we do?” hissed Gelio.
“We keep our wits about us,” Muko hissed back. “He mustn't know that we know.”
The door through which they had entered was at the back of the classroom. Pythagoras had walked to the front and was now standing watching them as they filed in, waiting for the last one to be settled. Behind him, next to the blackboard, a curtain partially concealed the dark entrance to a passageway. The room was lined with multiple cabinets on whose shelves were ranged mathematical instruments of every sort: solids,