He said this with a smile as he handed the coat to her. As she slipped it on, though, his words lingered. Nobody will ask you what you’re doing. You can do what you like. If, for any reason, there was a mischief-maker in the hospital, then the way would be wide open for such a person to do what he liked. The thought had a strangely chilling effect. It would take a particular sort of evil, she imagined, to prey on patients in a hospital; but such things happened—the unimaginable did occur. Fortunately she had never encountered it, but perhaps that innocence of experience would inevitably be shattered if one was a detective, which, after all, she claimed to be. But I’m not that sort of detective, she told herself; not that sort…

In her white coat, tight at the arms, she remembered how on another occasion, at the very beginning of her career, she had impersonated a nurse to deal with the bogus father of Happy Bapetsi. That had worked, and the greedy imposter, who had claimed to be Happy’s father, had been sent to Lobatse whence he had come, Mma Ramotswe’s denunciations ringing in his ears. That had been a simple investigation, though, requiring no more than the wisdom of Solomon, and she had always had a clear idea of what she had to say, the lines she had to deliver. Her current circumstances were of course very different. She had no idea what she was going to say or do, or indeed of what she was looking for. She was searching for something unusual, something which had occurred at the same time on three Fridays, but she could not imagine what this might be. When she had asked the staff in the ward if anything special happened at that time of the morning, and on Fridays in particular, they had looked blank. “We have our tea round about then,” one said. She had seized at this. Would nobody be looking after the patients while the nursing staff gossiped over a cup of tea? Her question had been anticipated. “We take turns to have tea,” somebody else had quickly assured her. “Always. Always. This means that there is always somebody on duty. Always. That is the rule.”