Mma Ramotswe picked up the nurse’s uniform from her friend Sister Gogwe. It was a bit tight, especially round the arms, as Sister Gogwe, although generously proportioned, was slightly more slender than Mma Ramotswe. But once she was in it, and had pinned the nurse’s watch to her front, she was a perfect picture of a staff sister at the Princess Marina Hospital. It was a good disguise, she thought, and she made a mental note to use it at some time in the future.

As she drove to Happy Bapetsi’s house in her tiny white van, she reflected on how the African tradition of support for relatives could cripple people. She knew of one man, a sergeant of police, who was supporting an uncle, two aunts, and a second cousin. If you believed in the old Setswana morality, you couldn’t turn a relative away, and there was a lot to be said for that. But it did mean that charlatans and parasites had a very much easier time of it than they did elsewhere. They were the people who ruined the system, she thought. They’re the ones who are giving the old ways a bad name.

As she neared the house, she increased her speed. This was an errand of mercy, after all, and if the Daddy were sitting in his chair outside the front door he would have to see her arrive in a cloud of dust. The Daddy was there, of course, enjoying the morning sun, and he sat up straight in his chair as he saw the tiny white van sweep up to the gate. Mma Ramotswe turned off the engine and ran out of the car up to the house.

“Dumela Rra,” she greeted him rapidly. “Are you Happy Bapetsi’s Daddy?”

The Daddy rose to his feet. “Yes,” he said proudly. “I am the Daddy.”

Mma Ramotswe panted, as if trying to get her breath back. “I’m sorry to say that there has been an accident. Happy was run over and is very sick at the hospital. Even now they are performing a big operation on her.”

The Daddy let out a wail. “Aiee! My daughter! My little baby Happy!”

A good actor, thought Mma Ramotswe, unless ... No, she preferred to trust Happy Bapetsi’s instinct. A girl should know her own Daddy even if she had not seen him since she was a baby.

“Yes,” she went on. “It is very sad. She is very sick, very sick. And they need lots of blood to make up for all the blood she’s lost.”

The Daddy frowned. “They must give her that blood. Lots of blood. I can pay.”

“It’s not the money,” said Mma Ramotswe. “Blood is free. We don’t have the right sort. We will have to get some from her family, and you are the only one she has. We must ask you for some blood.”

The Daddy sat down heavily.

“I am an old man,” he said.

Mma Ramotswe sensed that it would work. Yes, this man was an impostor.

“That is why we are asking you,” she said. “Because she needs so much blood, they will have to take about half your blood. And that is very dangerous for you. In fact, you might die.”

The Daddy’s mouth fell open.

“Die?”

“Yes,” said Mma Ramotswe. “But then you are her father and we know that you would do this thing for your daughter. Now could you come quickly, or it will be too late. Doctor Moghile is waiting.”

The Daddy opened his mouth, and then closed it.

“Come on,” said Mma Ramotswe, reaching down and taking his wrist. “I’ll help you to the van.”

The Daddy rose to his feet, and then tried to sit down again. Mma Ramotswe gave him a tug.

“No,” he said. “I don’t want to.”

“You must,” said Mma Ramotswe. “Now come on.”

The Daddy shook his head. “No,” he said faintly. “I won’t. You see, I’m not really her Daddy. There has been a mistake.”