ZOMBIES are big at the moment, from the cult American TV show The Walking Dead to the soon-to-be released World War Z at the box office; it seems that we can’t get enough of walking, brain-chomping ghouls from beyond the grave.

With the Zom-B series of books Darren Shan can hardly be described as jumping onto the band-wagon as his list of credentials as a horror writer for a teenage audience is long and impressive including thrillers like the Cirque du Freak Trilogy.

After the brutal, fast paced Zom-B, which I disliked, I wasn’t expecting much from this second instalment but was pleasantly surprised. Shan really hits his stride with Zom-B Underground. Shan’s teenage audience should be delighted with this latest book. It is just as gory but much more thought-provoking.

I thought there were some flaws with Zom-B, which kicks off a series of 12 books being released roughly every three months by Shan.

The main characters (a big gang of racists) are so unlikable you don’t really care what happens to them. In fact I was actively rooting for the zombies to eat the majority of them by the end. But on the plus side it was a real page turner and very easy to read (I read the whole thing in one evening.)

Zom-B Underground, also with a beautiful cover, is much better. The thought-provoking issues Shan tried and didn’t quite address in the first book - racism, the abuse of power and so on – are dealt with more thought, and the reader is also thrown into the thick of the action from the very first chapter.

In this book you do genuinely care what happens to the so-called heroine, the racist, undead B and what she has to deal with. After having her heart ripped out she is quickly re-animated but has retained all her human qualities. She is not a mindless shuffling or running manic killer, but it turns out that she is not far from being one.

She has to deal with all sorts of problems after being reanimated and institutionalised. With a group of other “reactives” (as they are called) she is made to torture and kill other zombies, who are now the new underclass. The narrative is told very much from the zombie’s point of view which leads you to think: who are the real monsters in this book?

Shan deals well with all the practical issues of being a zombie. The fact that she constantly has to use eye-drops to keep her eyes from drying out; she has to have her teeth filed down and her sluggish blood flow has a number of side effects. And then there’s the question of what they need to eat, all clever stuff.

Lots of questions still remain, what caused the zombie apocalypse? Where is owl man? Who is clown man? Is her racist dad still alive? Will he crop up again? Where will B get her next decent meal from?

There is a still lot to discover in this world Shan has created and teenage readers – and older ones too - will be bloodthirsty for the release of the next book.