Mr. Polopetsi started to give his answer, but said very little before his voice trailed off. “I re-invested it. My colleague had another…”

She saw his face fall.

“Your colleague? The same man?”

Mr. Polopetsi nodded.

“You gave him back the money?” said Mma Potokwane. Her tone was openly incredulous.

Mma Ramotswe winced. “He has another scheme?”

Mr. Polopetsi looked like a schoolboy whose unlikely story has suddenly been questioned. “Yes,” he said. “He told me he had the chance to buy a consignment of medicines from Zambia. He said that he could get these at a very low price and he knew people who would be able to sell them here in Gaborone at a much higher price.”

Mma Ramotswe heard Mma Potokwane’s sharp intake of breath.

“What medicines?” asked the matron. “Aspirin?”

Mr. Polopetsi laughed. “No, nothing like that. Antibiotics, he said. Blood pressure drugs. That sort of thing.”

“And why would they be cheap?” asked Mma Ramotswe.

Mr. Polopetsi shrugged. “Over-orders, probably,” he said. “Sometimes hospital dispensaries order far too much stuff and then realise they won’t be able to use it all. I suspect it will be something like that.”

Mma Ramotswe raised an eyebrow. “I see,” she said quietly.

“I’m going to help him,” he said. “He can’t get away and so he asked me if I could collect them from the other side.”

“The other side of the border?” asked Mma Ramotswe.

Mr. Polopetsi nodded. “Yes,” he said. “I’ll go up to Chobe. He’s going to hire a car for me. He said that he’d order some chemicals for the school lab and his order could go in with mine. That would be very useful for us, you see—the school is always running out of the things I need for my chemistry lessons.” He smiled; people understood—and sympathised with—administrative inefficiency on the part of others. It was a common burden. “These would be a donation from him.”

Mma Ramotswe hardly dared meet the intense look Mma Potokwane sent in her direction, but when she did she knew that they both had exactly the same understanding of what Mr. Polopetsi had said. It was so obvious, she thought; so glaringly obvious. She opened her mouth to speak, but Mma Potokwane had beaten her to it. “Oh, Mr. Polopetsi,” she exclaimed. “How could you, Rra? How could you be so stu—”

“So unwise,” said Mma Ramotswe quickly.

Mr. Polopetsi looked at Mma Potokwane and then at Mma Ramotswe. He seemed confused now, and remained in that state until Mma Potokwane, taking a deep breath, spelled out to him what she thought. Once she had done that, there was complete silence, and nobody said anything for at least five minutes. Then Mma Ramotswe cleared her throat. “I shall deal with this,” she said firmly.