This review contains lots and lots of spoilers!!
This book opens with Cassie, Zombie/Ben and crew taking refuge at an abandoned hotel where they were supposed to meet Evan. Everyone pretty much assumes that Evan is dead, but Cassie won't give up hope. Ben sends Ringer off to look into another spot for them to hole up because winter is coming and they'll need better shelter.
This book is also told from Ringer's POV (which is awesome because Ringer rocks). Teacup follows Ringer, but Ringer accidentally shoots her. Sad. And then they're discovered by the alien military people. Ringer could leave Teacup alone, but she decides to be caught too so Teacup doesn't have to face it alone. They put Ringer through all sorts of brainwashing, but she still doesn't give in. Eventually they implant her with the "hub," which augments her immune system and makes her even more badass. She develops feelings for the human military guy who's watching her - Razor/Alex. He helps her escape. But then he betrays her! *gasp* He was on Vosch's side the whole time - Vosch wanted to test the hub and her "escape" was the perfect way to do that. But maybe he's not totally on Vosch's side. He's left alone to guard her and tells her to run. She says she won't as long as Vosch has Teacup. When they get back to base, Razor shoots Teacup so she won't have any reason not to run. And she runs.
Evan obviously is still alive. He runs into Grace, another alien like him. She beats him up pretty bad, but he escapes, although his super immune system has crashed. And meets up with Cassie and crew. But Grace follows. And the aliens find them. Instead of destroying them though, they deliver a little girl to them. Evan says she's been implanted with a bomb that will detonate when it comes into contact with CO2. That's the aliens new plan - send in children bombs that will detonate when they're in close contact with multiple humans. They're able to get the bomb out of the girl, but then Grace shows up. Evan tells them all to leave. They do, but Poundcake, who's been shot, goes back and detonates the bomb. Grace is probably killed, but Evan might be too! Except, at the very end, we're pretty sure that he finds Cassie et al.
The big bombshell that Ringer finds out is that the aliens aren't actually aliens. They don't have alien consciousnesses downloaded into them. They had something implanted that made them think they did! OMG But Vosch is something else. Is he an alien?