Charlie appeared at the door, an adjustable wrench in his hand. “I am very busy, Mma,” he said. “What is it?”

“This letter, Charlie. You said that somebody left it. Who left it?”

Mma Ramotswe frowned. She knew the answer to Mma Makutsi’s question; the letter would have been found on a surface somewhere in the garage, slipped there by Mr. Polopetsi, so that it might be thought that somebody had dropped in unobserved. As a detective, even if only an assistant detective, Mma Makutsi should have realised that one could not assume that the letter had come from outside.

Charlie shrugged. “Some woman,” he said. “It was while we were dealing with that car under the tree—all of us. I came back to get something and I saw her coming out of the garage. I asked her what she wanted, but she just muttered something about making a mistake. Then she went off.”

Mma Ramotswe sat quite still. It was a woman. It was not Mr. Polopetsi.

“Are you sure that she left it?” she asked. “Are you sure it wasn’t there before?”

Charlie seemed surprised that such interest was being taken in the details of what he thought was a very unimportant matter. What did it matter who left a letter? It would be perfectly obvious who had written it—letters bore signatures, after all. “Yes, I am sure, Mma. It was on the petrol drum. I had been sitting on top of that before I went outside. There was no letter there. Then there was. It was that lady.”

“And you saw her face?” asked Mma Ramotswe.

“Yes,” said Charlie. “She was a very pretty woman. Big bottom too.”

“You think of nothing but bottoms,” snapped Mma Makutsi. “You are like a little boy.”

“Oh yes,” said Charlie hotly. “So there are lots of bottoms about. So that’s my fault, is it?”

“You must not fight about…about unimportant things,” said Mma Ramotswe. “It is not right.” She made a placatory gesture to Charlie. “Now listen, Charlie, you didn’t recognise this lady, did you? Had you seen her before?”

Charlie shook his head. “No. Never.” He cast an angry glance at Mma Makutsi. “Can I go now, Mma Ramotswe?”

“Of course you can, Charlie,” said Mma Ramotswe, adding, “and thank you. Thank you for helping me to avoid making a big mistake.”

After Charlie had left, Mma Makutsi returned to sit down at her desk. She looked at the letter once more, and then shifted her gaze over to Mma Ramotswe. “So, Mma Ramotswe,” she said. “It was not Mr. Polopetsi after all.”

Mma Ramotswe looked down at her hands—the hands of one who was capable, she realised, of the most appalling mis-judgement. “I feel very bad, Mma,” she said. “I feel very bad to have thought those things about him. It was very unfair.”

“Yes,” said Mma Makutsi. “It was.”