A black robot

On Friday afternoon, Amira and Wei Jie took a bus to Northfield Academy. If Silver Blaze had left the school, Amira reasoned, it could not be far away, and the only people who wanted it to miss the championship were at Northfield.

Northfield's robotics teacher, Mr Brennan, was a large man with a brusque manner. "We're busy," he said at the door of his workshop. "Your robot isn't here. Go home."

Behind him, his students looked sullen and would not meet Amira's eyes.

On a table at the back stood a robot she had never seen before. It was painted black, with a red stripe down one side. It was the right size, though. And when Amira looked closely, she saw a tiny patch of silver at one corner, where the paint was already coming off. Under it, the surface was still as pristine as on the day Silver Blaze was built.

"That's ours," she said quietly. "You've painted it. The black paint is just camouflage."

Mr Brennan's face went red. At first he was adamant that the robot belonged to Northfield. Then Inspector Lim arrived, and he told the truth. Early on Friday morning, driving to work, he had found the robot at the side of the road between the two schools, a little scratched but still working. He had always coveted Silver Blaze. Instead of returning it, he had painted it, planning to keep it hidden until the championship was over.

It was a devious plan, but not a clever one. "I didn't steal it," he kept saying. "I found it."

"Then who left it by the road?" asked Wei Jie.

Amira had an uncanny feeling that the answer was back at their own school. Mr Brennan's subterfuge explained where the robot had gone. It did not explain how it had got out of the lab.