The Dragon Factory picks up shortly after the events of Patient Zero as the Department of Military Sciences is faced with a new, completely different threat. This time around there is no zombie plague but rather a planned extinction wave targeted to wipe out a specific large portion of the human population. With the concepts of eugenics, genetic manipulation, and disease weaponization all taken to mad scientist levels the DMS must beat the clock to figure out who is behind the threat and neutralize it before the Extinction Clock counts down to zero. The story is a bit more complex than the first book and therefore starts slower but it eventually comes together and builds to a satisfying crescendo.

Many of the major characters from Patient Zero return including Joe Ledger and the rest of Echo team, Mr. Church, Dr. Hu, Bug, Rudy Sanchez, and Major Grace Courtland. As the relationship between Joe Ledger and Major Courtland grows they both need to work hard to prevent it from negatively impacting their jobs. Grace and Joe both have their characters developed as more is revealed about the past events that shaped them into what they are today. The warrior, the modern man, and the detective make up the three personas that war within the mind of Joe Ledger and each struggles for dominance. The stress of life as a DMS agent while being in a relationship that tugs on the scars of his past is a constant threat to Ledger's self control and his ability to keep it all together.

With a whole new cast of bad guys the story takes quite a bit of time at the beginning to build up a tangled web of interconnected threads into a coherent plot. We learn quickly that the Jackoby twins are using genetic manipulation to create fantastical creatures straight out of mythology, including unicorns and dragons. Oddly enough this is what gets the attention of the DMS and leads them to unravel a much more threatening big picture with disturbing ties to the past. It is hard to get into too many details without giving away key plot points but the story goes from mythical creatures to a planned human extinction wave that ties back to the efforts of the Third Reich.

It all eventually comes down to a tense race against the clock for the DMS, with both Joe Ledger and Grace Courtland leading their teams into the field to try to save the day. While I felt that the story was not quite as good as the first book, it was still very enjoyable and the character building was well done. Ray Porter delivers another excellent narration for the audiobook and I found myself eager to move forward in the series when this one was all said and done.