There are whispers in metaspaces all through Excelsior about disappearing young adults. They're the ones who would absolutely be in the crowd's of Bruce's street races. He'll notice a young man with iron skin passing out missing persons posters in the crowd, looking for his sister - her body is made of quicksilver - the last he heard, she had an appointment with a doctor to see about making her skin less toxic to the touch. Given she still lives at home, her disappearance is... extremely worrisome.

He has an address that she had provided to him before leaving for the appointment, but it leads to an old abandoned pharmaceutical building. It does look like someone had recently been inside of it and had cleaned out the reception area, as well as utilized one of the rooms, but aside from some trash left behind in a garbage can(a needle, latex gloves, several paper towels covered in a metallic substance) there won't be too many clues to track down.

Bruce might be able to get information by tracking down doctors associated with metacommunities, following the trail of some of the missing metahumans, or seeing what he can find at the building. Let us know what path he'll try, and we can provide further information!