This is kind of what I was saying yesterday. There is someone more significant that Sprengstoff in this story, but we haven’t yet seen who it might be. In a more typical Tracy story, we would already know.
All jokes aside, it’s actually up-to-date technology in a retro package. The Wrist TV was long ago replaced by a couple of new generations, but the latest one developed an exploding battery problem and Diet Smith went back to this old-style exterior, temporarily, several years ago. It doesn’t have a screen but it can project an image into mid-air behind it.
So, it seems that Sprengstoff might have been working for someone, but whether he was working for Daddy “I’ve never heard of him” Totten is still up in the air. It seems that Sprengstoff may have been up to no good, but we still don’t really know what crime he may have been planning. It’s a bit of a weird plot.
I think the point is that she’s not on her way, because this is still a murder in the city at this point, still local jurisdiction.