“Wait a moment, Mma,” said the imaginary Mma Makutsi. “All you know, Mma Ramotswe, is that the late mother told somebody that she was not the mother. Does that mean we can say for sure that Mma Sebina was not the daughter of that lady? Does it really mean that, Mma?”

It was an unexpected question, but it made Mma Ramotswe pause. She had often taken Mma Makutsi to task for assuming things too readily, and now here was her assistant accusing her of exactly the same thing.

Her eyes still firmly shut, Mma Ramotswe spread her hands in a gesture of acceptance. “You’re quite right, Mma,” she said. “It is possible that the mother—that is, the lady who was known as the mother—was really the mother after all and was lying when she told that other lady that she was not. That is possible, I think.”

Mma Makutsi shook her head. “No, Mma,” she said. “You have misunderstood me. Perhaps the lady who said that the other lady said that thing—perhaps that is the lady who was making up the story. That is what I meant.”

Mma Ramotswe smiled. “Why, of course! A real mother would not lie about such a matter, particularly when she was very ill and would shortly be called to account for all her lies, if she had any. She would not lie then, even if she had been a liar before, would she?”

“Excuse me, Mma.” It was not Mma Makutsi’s voice, but another voice altogether, and Mma Ramotswe opened her eyes with a start. Mr. Polopetsi, the general assistant at the garage and their occasional helper in the agency, was standing in the door, framed by the morning sunlight, an empty mug in his hand.

“I heard you talking,” he said. “And I knocked. Like this. Knock, knock. But you did not hear me. You were busy talking to…to…”

His embarrassment was evident, and Mma Ramotswe, although herself embarrassed to have been found talking to herself, sought to reassure him.

“To Mma Makutsi,” she said. “I was talking to Mma Makutsi, Rra.”

Mr. Polopetsi glanced at Mma Makutsi’s empty desk. “I see.”

Mma Ramotswe laughed. “No, she is not there, Mr. Polopetsi. There is no Mma Makutsi. I was thinking of what I would say to her, you see. I was imagining that we were talking to one another. But she is not there…as you can see,” she ended lamely.

“No, she is not there,” said Mr. Polopetsi, advancing towards the teapot. “That is correct. She is not there, Mma.”

“Exactly,” said Mma Ramotswe. “But I closed my eyes to imagine that she was there, because I needed to know what she would think about something.”

“I see,” said Mr. Polopetsi as he filled his mug with tea from Mma Ramotswe’s teapot. “But who is this lady who has no mother?”