The Tribulation Force has been forced literally underground, scattered across the country, due to the extreme crackdown of the GC on those not bearing the mark of loyalty. The great battle of Armageddon is nearing, and Nicolae Carpathia has begun gathering all those loyal to him to defeat Jesus and his followers in the valley of Armageddon. The Tribulation Force soon finds that they must relocate to Petra due to the captures of Chloe and Albie. As the times become more evil and the end of the world is on the horizon, the Trib Force does not know whether or not they can stay sane enough until the Glorious Appearing.
The authors have drastically turned the series around by pulling it out of its second nose dive The Remnant created. Armageddon is a return to the originality of The Mark because the authors were not afraid to kill off a few very key characters.
Chloe and Albie suddenly become imperfect characters, because it is their fault that they get captured; they are not victims of circumstance. This is the first book of the series that eliminates four characters and does not add any new ones. No other characters really undergo any major changes. This is not a character-based book, but a plot-driven book, following the theme of the series. With only one book left in the series, the characters obviously aren't going to get any better than this.
Without the captures of Chloe and Albie, there would not be much to talk about in this book. The authors probably realized this and decided that it was time to do something original. It was high time, because such originality has not been used since The Mark. As usual, end times elements are presented well. This is the point in the series when lesser known events occur, and the authors did a good job of finding those such events and portraying them. There are four key character deaths in the book, but one of them is unknown, making the best end of any book of the series. It was better than any other end because it did not force suspense upon the reader. It is a mysterious end that actually made me want to read the next book. The series really should end with this book because I doubt Glorious Appearing will come up with a better one. But this is a futile hope because the authors are not going to cut the series off here.
One can assume that this will be the last interesting book of the series because from here on out, the authors can begin using creative licence as a shield. But Armageddon was enjoyable nonetheless because it exhibited elements the authors should have been using all along.