“I worked down there for twelve years before they sent me up to Gaborone. I was very pleased to get this new job because it was more senior and I was given more money. I became a pharmacy assistant at the Princess Marina, which is a very fine hospital. There is a very big pharmacy there and they have many, many shelves of bottles. I worked very hard and did well. Now I could marry a lady whom I had met at my church. She is a very good lady and she has given me two children, two girls, this big and this big, and they are very good children.

“I was a very happy man and a very proud one too. Then one day a very bad thing happened to me, a thing which changed my life forever and which I can never forget. And it was just an ordinary day, the same as any day. When I left my house that morning I did not know what was going to happen to me. I did not know that this was the last day that I would be happy.”

Mr Polopetsi paused to bite into the fresh sandwich which Mma Makutsi had passed him. He took a large mouthful, and the two ladies watched him in silence as he chewed on the food. Mma Ramotswe wondered what it was that could have suddenly brought his world to an end. He had said when they had first met them that there had been an accident, but what accident could have resulted in his spending two years in prison? A road accident? Had he driven while drunk and killed somebody? He seemed an unlikely candidate for that.

“We were very busy that morning,” continued Mr Polopetsi, wiping crumbs from his mouth with the back of his hand. “Sometimes it was like that. All the wards would run out of medicines at the same time and there would be a whole line of out-patients waiting for their prescriptions. So we would be running this way and that, trying to get things sorted out. There were two pharmacists who were ill that day because there was a lot of flu in the town. So we were very busy.

“We were not allowed to do many things. We were just pharmacy assistants, and so we were not allowed to measure out drugs and things like that. But when it was busy like that they sometimes told us that we could do simple things, like counting out pills and putting them in bottles. So we did that.

“I was doing that sort of thing on that morning. And that is when I made a mistake. I took pills from the wrong place and put them into the bottle which the pharmacist had given me. I put these pills in because I thought that he had pointed to one place and not to another. I misunderstood him.