Sally had heard of a boy in Omaha who could see through walls. There was a girl in Los Angeles who could fly, and one in London who could turn into a liquid.

Scientists were talking about ‘artificial evolution’, though nobody was sure of the cause. Sally knew that what they really were was mutants. Last week she had discovered that she was a mutant, too. It was less exciting than she had hoped.

Her power didn’t make her invincible; in fact, it was difficult to imagine any circumstance where it would help her fight crime. She could identify birds without ever having seen or even heard of them before. It was hard not to feel ripped off.