Harbinger is a sequel of Homecoming. Here you get to know the survivors of the bombing and see them trying to cope with life ten years after the incident. Once again you follow several characters and the more their stories evolve the more it's obvious that they all are in danger. It's very interesting to read how they find out what's behind all the incidents and how some of them work together per chance to solve the big mystery. The 'big bang' though is told a tiny bit too fast, like short quick glimpses... but as the whole story was more about the survivors of the bombing/their families this is absolutely fine. Harbinger is a must-read when you've read Homecoming. And the paranormal approach makes it even better. A well done Duology.