They began to make their way towards the house. “He is a very good gardener,” said Mma Makutsi. “He doesn’t speak very much, as you can see, but he is very good at growing things. He comes from Lobatse. He used to have a job in the hospital for mental illnesses. He was a gardener there.”

“Oh yes,” said Mma Ramotswe. “I think the patients like to work in the gardens. It helps them to get better.”

“In some cases,” said Mma Makutsi. “In other cases it is not much help. Mr. Moepi told me that one of the patients hit him over the head with a rake.”

“I’m sorry to hear that,” said Mma Ramotswe.

“Yes. But these things happen, Mma. Nobody is to blame.”

Mma Ramotswe assured Mma Makutsi that she had not been thinking in terms of blame.

“You see,” continued Mma Makutsi, “if you’re confused you may not know what you’re doing. It’s like being asleep. Then you wake up and you find you’ve done something you didn’t mean to do.”

Mma Ramotswe nodded. “That must be true, Mma. It must be very sad for these people.”

They reached the house. Itumelang, Mma Makutsi said, was sleeping, but Mma Ramotswe could peek in on him if she wished.

“I’d love that,” said Mma Ramotswe. “But first, Mma, we must talk. You and I must talk.”

Mma Makutsi stiffened. “About this Mma Susan business?”

Mma Ramotswe nodded.

They were on the verandah; Mma Makutsi indicated a corner where three chairs were ranged around a table. “We can sit there, Mma. It’s a good place to talk.”

Once seated, Mma Ramotswe took a deep breath and began. “I need to tell you something, Mma Makutsi,” she began. “I think I’ve been wrong.”

Mma Makutsi, who had been frowning, now smiled. “About that Mma Rosie? Yes, Mma, I thought you were wrong. I am sometimes wrong myself, you know, and I’d be the first to admit it, but this time I thought, Mma Ramotswe is wrong. That’s what I thought, Mma.”

“But not about Mma Rosie,” said Mma Ramotswe hurriedly. “Or maybe wrong about her as much as I was wrong about Mma Susan. She is the one I may be most wrong about.”

This confused Mma Makutsi. “Mma Susan? Why are you wrong about her?”

Mma Ramotswe sat back in her chair. “Of course I may be wrong in thinking I’m wrong. That’s also possible, Mma.”

“No, I think you’re right,” said Mma Makutsi. “I think you’re right about you thinking you’re wrong.”

They looked at one another for a moment, and then Mma Ramotswe laughed. “You never know, do you, Mma?” she said. “You never know when being wrong is right.”