A large car, covered in the ubiquitous thin layer of dust that settled on everything in the dry season, had drawn up and a thin, white woman, wearing a khaki blouse and khaki trousers, had stepped out of the passenger seat. She glanced up briefly at the sign on the front of the building, took off her sunglasses, and knocked on the half-open door.

Mma Makutsi admitted her to the office, while Mma Ramotswe rose from her chair to welcome her.

“I’m sorry to come without an appointment,” said the woman. “I hoped that I might find you in.”

“You don’t need an appointment,” said Mma Ramotswe warmly, reaching out to shake her hand. “You are always welcome.”

The woman took her hand, correctly, Mma Ramotswe noticed, in the proper Botswana way, placing her left hand on her right forearm as a mark of respect. Most white people shook hands very rudely, snatching just one hand and leaving their other hand free to perform all sorts of mischief. This woman had at least learned something about how to behave.

She invited the caller to sit down in the chair which they kept for clients, while Mma Makutsi busied herself with the kettle.

“I’m Mrs Andrea Curtin,” said the visitor. “I heard from somebody in my embassy that you were a detective and you might be able to help me.”

Mma Ramotswe raised an eyebrow. “Embassy?”

“The American Embassy,” said Mrs Curtin. “I asked them to give me the name of a detective agency.”

Mma Ramotswe smiled. “I am glad that they recommended me,” she said. “But what do you need?”

The woman had folded her hands on her lap and now she looked down at them. The skin of her hands was mottled, Mma Ramotswe noticed, in the way that white people’s hands were if they were exposed to too much sun. Perhaps she was an American who had lived for many years in Africa; there were many of these people. They grew to love Africa and they stayed, sometimes until they died. Mma Ramotswe could understand why they did this. She could not imagine why anybody would want to live anywhere else. How did people survive in cold, northern climates, with all that snow and rain and darkness?

“I could say that I am looking for somebody,” said Mrs Curtin, raising her eyes to meet Mma Ramotswe’s gaze. “But then that would suggest that there is somebody to look for. I don’t think that there is. So I suppose I should say that I’m trying to find out what happened to somebody, quite a long time ago. I don’t expect that that person is alive. In fact, I am certain that he is not. But I want to find out what happened.”

Mma Ramotswe nodded. “Sometimes it is important to know,” she said. “And I am sorry, Mma, if you have lost somebody.”

Mrs Curtin smiled. “You’re very kind. Yes, I lost somebody.”

“When was this?” asked Mma Ramotswe.