The premise behind Hosts is that there's this virus, called Unity, that turns people into a sort of hive mind thing that wants to take over the world. It's not exactly an original idea. It kind of reminded me of the Doctor Who episode The Invisible Enemy, only the virus doesn't make people look like chipmunks. I also thought of the Borg, only they used nanites and turned into cyborgs. There are probably a bunch of other places that use the same idea, but that doesn't mean this one sucks.
This one has Repairman Jack--and his sister Kate. Kate's lesbian lover is infected with the virus and Kate is worried about her. So Jack steps in to help. Turns out Jack's immune to the virus due to his encounter with the Rakoshi back in The Tomb. Anyway, the day is saved and unfortunately Kate dies tragically. I already knew that she would though, because it was mentioned in Infernal.
The idea behind the story wasn't a particularly original one, but then very few are. This is actually a very good book. The Repairman Jack books are always exciting. The only thing I regret about reading this one is that now I only have three more Repairman Jack novels to read (not counting Nightworld). I'm not counting Nightworld, because I don't plan on reading until I can get my hands on a revised edition--the older version was written before the Repairman Jack books 2+, and from what I hear the continuity no longer makes sense--and unfortunately, as far as I can tell the revised Nightworld is currently only available in a $60 limited edition version, and that's a little out of my price range.
To get back on track, Hosts is a darn good book. I love these Repairman Jack books, and I don't hesitate to give this one a full five yo-yos.