Nightshade is a team of highly-trained military black-ops specialists. In the case of Nightshade, they are so black that they don’t officially exist - except that someone in power not only knows of their existence, but is out to destroy them. One team member, Griffin, has been falsely imprisoned for murder, while the others are ambushed and taken prisoner by unknown assailants attacking their headquarters. Their wives and children are taken to a government safe house, and their boss has disappeared. Help comes in an unlikely form – Kacie, a woman with a dark past and a mix of skills that seems to include everything from gymnastics to breaking Griffin out of his super-maximum security prison. But who is Kacie working for, and can she be trusted?One of the features of thriller/suspense novels is the relative complexity of the plot (well, compared to romance or romantic suspense). The first few chapters of a thriller inevitably introduce three or four sets of characters in different places and with no apparent connection. As the plot progresses, the connections between the characters and sub-plots are gradually revealed to the reader. But one of the problems with this structure is that the reader often develops a preference for one aspect of the story (for me, this is the sub-plot with the most likelihood of becoming a developing romance), and it can be quite jarring to be force to move onto the next sub-plot just when something interesting is about to happen (like a kiss).Another disadvantage of a large number of sub-plots is the large number of leading and supporting characters. This gets particularly confusing when a significant number are ex-military, so have three names: their first name (used by wives and non-combatants), their surname (used by their superior officers), and their nickname (used by their colleagues). Sometimes a single character will be addressed by two different names on the same page, which adds to the confusion: who is who? Several of the characters also have wives, children and siblings involved – more names to remember. I felt like I should have been taking notes to keep all the names, roles and relationships straight in my head. This, to my mind, is too much complexity. It’s not as though I can’t process the information. Rather, it’s that I don’t want to, because I read for enjoyment, and too much confusion is taxing on my mind, not enjoyable. Despite all that, I did enjoy Firethorn. The plot was well constructed, there were a cast of super-hero good guys, suitably evil bad guys, plenty of action, a little romance, some soul-searching and an underlying theme of redemption through Christ.This is the fourth and final book in Ronie Kendig’s Discarded Heroes series, following Nightshade, Digitalis and Wolfsbane. In a note to the reader at the end of the book, Kendig says that as it is the final book, she has deliberately reintroduced characters from throughout the series to show the reconciliation of family relationships. In this, she has been successful, but, as someone who has not read the previous books, I found the large cast of characters confusing. However, this statement is also a relief, in that it suggests that this level of complexity is not typical of her books in general, so I will be keen to try another of her books to find out! (Her stand-alone, Dead Reckoning, has been sitting on my to-read pile for a while…)Thanks to Barbour Publishing and NetGalley for providing a free ebook for review.This review also appears on my blog, www.christianreads.blogspot.com.