After Mr Polopetsi had left, Mma Ramotswe smiled at Mma Makutsi. “He is a good detective, that man,” she said. “He would be a very good assistant for you, Mma Makutsi.”

Mma Makutsi welcomed this. She relished the thought of having an assistant, or indeed anybody who was junior to her. She had done a course in personnel management at the Botswana Secretarial College and had secured a very good mark in it. She still had her notes somewhere and would be able to dig them out and read them through before she started to exercise actual authority over Mr Polopetsi.

“But now,” said Mma Ramotswe, glancing at her watch, “I have a medical appointment. I mustn’t miss it.”

“You aren’t ill, are you, Mma Ramotswe?” enquired Mma Makutsi. “This diet of yours …”

Mma Ramotswe cut her off. “My diet is going very well,” she said. “No, it is nothing to do with the diet. It’s just that I thought I should go and have my blood pressure checked.”

IT HAD BEEN EASY to find out which doctor Boitelo had been talking about. She had let slip, without thinking, that he was Ugandan, and that his clinic was close enough to where she lived for her to walk to work. She had Boitelo’s address and that meant a simple trawl of the list of medical practitioners in the telephone book. The Ugandan names were easily enough spotted—there were a number of them—and after that it was a simple matter to see that Dr Eustace Lubega ran a clinic just round the corner from the street in which Boitelo lived. After that, all that was required was a telephone call to the clinic to make an appointment.

It had been Boitelo who answered the telephone. Mma Ramotswe announced who she was, and there was a silence at the other end of the line.

“Why are you phoning this place?” said Boitelo, her voice lowered.

“I want to make an appointment—as a patient—with your good Dr Lubega,” said Mma Ramotswe. “And don’t worry. I shall pretend not to recognise you. I shall say nothing about you.”

This reassurance was followed by a brief silence. “Do you promise?” asked Boitelo.

“Of course I promise, Mma,” said Mma Ramotswe. “I will protect you. You don’t need to worry.”

“What do you want to see him about?” asked Boitelo.

“I want my blood pressure checked,” said Mma Ramotswe.