So I thought an awful lot of the plot was telegraphed, even though Toby was missing all sorts of things for most of the book, and the non-murderous people at ALH (the company) were missing all the things that they weren't actively hiding from Toby.
It was pretty clear less than a quarter of the way into the book that Alex and Terrie were more or less automatically seducing Toby and Quentin. About halfway through it, I began to suspect that they were the same person.
The telephone situation was suspicious to me long before it was suspicious to Toby.
April was my number one suspect for the murders when I was about 70% of the way in, although there wasn't any motive. But I was pretty sure that the fact that she didn't understand normal living beings was going to be involved.
Gordan as a suspect occurred to me at roughly the same time. And then I double-thought myself away from her because she so obviously disliked Toby and Quentin that it was somehow too easy to think of her as a murderer.
It was also clear, less than halfway through, that the ALH staff were lying through their teeth about a lot of things.
I don't know whether I've ever mentioned that I used to read a lot of mysteries, ranging from Heron Carvic's cozy "Miss Seeton" series to Ed McBain's hard-boiled police procedurals. I don't think McGuire played very honestly here with the core of the mystery. I don't believe that there was any way that a reader could have anticipated Gordan's motivation, nor how deranged she was.
What ALH – and Gordan in particular – was trying to accomplish has been explored before in stories I've read. C.J. Cherryh's Voyager in Night come to mind, for example.
Still, I enjoyed the ride while I was on it.