Your enjoyment of this new Torchwood book probably depends largely on how much you enjoyed the TV show's fourth series, Miracle Day. If you hated it this isn't for you. If you thought it was OK though this is a decent follow up. It sees a new disaster for Earth where woman are having breakdowns and hydrothermal vents are popping up instantaneously all over the world. It doesn't look good.
The use of the main characters in this book is pretty atrocious. Gwen is one of the women having a breakdown and whilst that gives a good window to the plot it means half of Torchwood is out of action. Rhys and Andy Davidson are both in it but as more minor characters their roles aren't very important. Captain Jack is the hero of the tale and whilst he is characterised well (who knows him better than John Barrowman, the actor who plays him) he spends most of the book out of it as well. Miracle Day's Rex Matherson makes a very fleeting appearance which seems unnecessary. Either use him or don't.
Having said that, some of the supporting cast is pretty good. A portion of the book is set on The Ice Maiden, a high tech boat with a crack team of scientists and thanks to Jack a holographic computer personality. It feels like a new Hub and team and I only wish their role had been used more.
The plot itself is in many ways like Miracle Day. Not a lot really happens for the first three quarters, it all building up to a decent but actually pretty easily solved finale. It's pretty global with large bits set in South America and although technically an alien is involved it's a sci-fi story without any aliens, again.
It's a decent effort from John and his sister and at least it continues the show whilst on it's everlasting hiatus but it doesn't quite work. Too long is spent on build up and the characters aren't used effectively and it's like they haven't learnt any lessons from the bad press Miracle Day got. 3/5