Mr Polopetsi, watching intently, swayed slightly and thought for a moment that he was going to faint. This was the sort of moment that he had imagined would arise in detective work: the moment of denouement when the guilty person faced exposure, when the elaborate reasoning of detection was revealed. Oh, Mma Ramotswe, he thought, what a splendid woman you are!

Aunty Emang did not move, but sat staring impassively at her accuser. When she spoke, her voice sounded higher than before, and there was a strange clicking when she started talking, like the clicking of a valve. “You are speaking lies, fat woman,” she said.

“Oh, am I?” retorted Mma Ramotswe. “Well, here are some details. Mma Tsau. She was the one who was stealing food. You blackmailed her because she would lose her job if she was found out. Then there is Dr Lubega. You found out about him, about what happened in Uganda. And a man who was having an affair and was worried that his wife would find out.” She paused. “I have the details of many cases here in this file.”

Aunty Emang snorted. “Dr Lubega? Who is this Dr Lubega? I do not know anybody of that name.”

Mma Ramotswe glanced at Mma Makutsi and smiled. “You have just shown me that I was right,” she said. “You have confirmed it.”

Aunty Emang rose from her chair. “You cannot prove anything, Mma. The police will laugh at you.”

Mma Ramotswe sat back in her chair. She put the pencil down. And she thought, How might I think if I were in this woman’s shoes? How do you think if you are so heartless as to blackmail those who are frightened and guilty? And the answer that came back to her was this: hate. Somewhere some wrong had been done, a wrong connected with who she was perhaps, a wrong which turned her to despair and to hate. And hate had made it possible for her to do all this.

“No, I cannot prove it. Not yet. But I want to tell you one thing, Mma, and I want you to think very carefully about what I tell you. No more Aunty Emang for you. You will have to earn your living some other way. If Aunty Emang continues, then I will make it my business—all of us here in this room, Mma Makutsi over there, who is a very hard-working detective, and Mr Polopetsi there, who is a very intelligent man—we shall all make it our business to find the proof that we don’t have at the moment. Do you understand me?”

Aunty Emang turned slightly, and it seemed for a moment that she was going to storm out of the room without saying anything further. Yet she did not leave immediately, but glanced at Mma Makutsi and Mr Polopetsi and then back at Mma Ramotswe.

“Yes,” she said.