An advertisement in the library

Maya first saw the notice on a wet Monday in November. It was on the library board, between a chess club poster and a photo of a lost water bottle.

"That is a very eccentric advert," Maya said. "Nobody normal pays people for the colour of their hair."

Arif said nothing. He was the only student in the school with bright red hair (his mother was Scottish), and he had heard every joke about it.

"Fifty ringgit is fifty ringgit," he said.

On Saturday he climbed the stairs of an old building next to a bank. Mr Lim was meticulous: every pen on his desk pointed the same way, and his shoes had no dust on them at all. He scrutinised Arif's hair for a long time, as carefully as a doctor looking at an X-ray. Then he smiled and gave Arif a giant dictionary.

"Copy it by hand. Start with A."

It was the most tedious job in the world: three hours of the same thing, again and again.

On Monday, Arif told Maya everything. "Maybe he's just a rich man who loves dictionaries." It sounded plausible. Not certain, but possible. Maya was not so sure.

"Why build such an elaborate plan, with an advert, an office and a dictionary, just to keep one boy busy?" she asked. "Unless the busy boy is the point."

Then Arif remembered one more thing. At exactly 11:55, a strange, inexplicable sound had come up through the floor. Mr Lim said it was old pipes, but pipes do not knock like that: slow and steady, like someone digging.