I thought this was a wonderful sequel to a really good first book in the series. In this sequel, we here about a girl called Sena, who is on a school trip with her class, on a cruise ship, when the EMP strikes. Naturally, this sends the ship into a sense of chaos, and we follow Sena's story from there.
I loved the link to the first book, and also enjoyed the idea that this book can also be read as a standalone, as things get explained from different perspectives.