Mr Polopetsi raised a finger in one of his characteristic gestures of emphasis. “You’ll never believe who she wrote to, Mma Ramotswe. You’ll never guess.”

Mma Ramotswe savoured her moment. “Aunty Emang?” she said quietly.

Mr Polopetsi looked deflated. “Yes. How did you know that?”

“I had a hunch, Mr Polopetsi. I had a hunch.” She affected a careless tone. “I find that sometimes I have a hunch, and sometimes they are correct. Anyway, that’s very useful information you came up with there. It confirms my view of what is happening.”

“I do not know what is happening,” said Mr Polopetsi.

“Then I will tell you, Rra,” said Mma Ramotswe, pointing to her office. “Come inside and sit down, and I will tell you exactly what is going on and what we need to do.”

BOTH MMA MAKUTSI and Mr Polopetsi listened attentively as Mma Ramotswe gave an account of where she had got to in the blackmail investigation.

“Now what do we do?” asked Mma Makutsi. “We know who it is. Do we go to the police?”

“No,” said Mma Ramotswe. “At least, not yet.”

“Well?” pressed Mr Polopetsi. “Do we go and talk to Aunty Emang, whoever she is?”

“No,” said Mma Ramotswe. “I have a better idea than that. We get Aunty Emang to come and talk to us. Here in our office. We get her to sit in that chair and tell us all about her nasty ways.”

Mr Polopetsi laughed. “She will never come, Mma! Why should she come?”

“Oh, she will come all right,” said Mma Ramotswe. “Mma Makutsi, I should like to dictate a letter. Mr Polopetsi, you stay and listen to what I have to say.”

Mma Makutsi liked to use her shorthand, which had been described by the examiners at the Botswana Secretarial College as “quite the best shorthand we have ever seen, in the whole history of the college.”

“Are you ready, Mma?” asked Mma Ramotswe, composing herself at her desk. She was aware of being watched closely by Mr Polopetsi, who appeared to be hanging on her every word. This was a very important moment.

“The letter goes to,” she said, “… to Aunty Emang, at the newspaper. Begin. Dear Aunty Emang, I am a lady who needs your help and I am writing to you because I know that you give very good advice. I am a private detective, and my name is Mma Ramotswe of the No. 1 Ladies’ Detective Agency (but please do not print that bit in the paper, dear Aunty, as I would not like people to know that I am the person who has written this letter).”

She paused, as Mma Makutsi’s pencil darted across the page of her notebook.

“Ready,” said Mma Makutsi.