I think this was a solid entry, but it didn't quite spark my imagination quite as much as the previous book in the series. This is is kinda surprising. I'd have thought that Alex mysteriously championing some spooky fringe science and parading it around as an unsolved mystery, much to Chase's annoyance, would be right up my alley, and as a matter of fact, it was. 
 What it actually became was also interesting even if it was kind of an old hat in the SF world, but never mind... any discussion of alternate universes or even colliding universes can make me and the characters in these novels laugh. But a pattern to missing spaceships? Well, now, there's something that people need to take seriously, and Alex does, and again he's proven right. Again. 
 I cannot say how much I approve of Chase being the narrator. Without her, these books might be pretty unbearable. :) BUT, on the other hand, this novel is pretty much riding on the coattails of the previous books in the series, relying on the things we already know to carry the characters, and I'm not complaining. It just proves that the fans are respected. 
 But what about the subplot? The AI rights? Well this one was pretty cool. I think the AI's have a really good case against humanity when it comes to criminal negligence. Over 7 thousand years of being left Home Alone might turn any Macaulay Culkin AI rather insane. Still, the resolution gives me a happy glow. :)