This is the fourth book in this colorfully-titled series. The Earth seems to be under attack and whoever is doing it is taking their time. The survivors Nick, Molly, Bronx and Gwen continue to try to find shelter along with a few others. As expected things don't go well including their capture by escapees from an asylum.
They have a general idea of where they are headed but it's obvious that they're going to continue having a hard time finding food, shelter and water and at the same time avoiding the crazies.
My main problem is with the concept of the series. If the red sky/blue cloud/black rain and white dust are really a form of alien attack then the aliens are rather stupid. If you want to wipe out all the humans just use major radiation attacks and then kill off what few humans survive those.
That all could be done rather quickly and efficiently.
If the aliens are trying to terraform the planet to their own needs then, again, they are going about it the wrong way. I think the series is getting to be a little boring.