Counter-terrorism has been a consistent theme over the first four books of this series but that doesn't mean the stories have been repetitive. Joe Ledger and the DMS have actually faced quite a variety of adversaries so far, including zombies, super soldiers, and vampires. In each case there has been a scientific rationale to explain the existence of these seemingly supernatural creatures thus Joe Ledger has learned the hard way that he must keep an open mind if he wants to stay alive. However, all of those lessons don't seem to help much as he begins to uncover the facts in his latest case. It all starts with an impossibility - the President of the United States is abducted from the White House and not a single secret service agent saw anything. The only piece of evidence left behind is a crop circle on the White House lawn but that has to be a hoax. Right?

The story arc continues as some of the villains from The King of Plagues are behind a new threat to the world based in the Middle East. In Iran for a rescue mission, Echo team and Joe Ledger are tipped off that seven, or more, nukes are in the hands of an ancient order known as the Red Knights and are currently planted around the world. With an end game that intends to turn the world into a radioactive mess the DMS has very little time to come up to speed and formulate a response. With Ghost at his side, Joe Ledger starts to reveal just who these Red Knights are and he is having a hard time believing what he finds. After all, vampires aren't real, right?

​​​​​​​The King of Plagues brings back some baddies from a prior book as the Department of Military Sciences discovers the existence of the Seven Kings. They are a powerful cabal bent on causing chaos throughout the world and profiting from it. The Seven Kings use their knowledge of the upcoming chaos they will cause to make money on various fronts as wars and catastrophes impact the world markets. Ruled over by "The Goddess" there are seven members of the cabal each with an advisor who acts as their "conscience." It turns out that they have a vacancy and are in need of a new King of Plagues.

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.

Some books take a while to find their legs and get going but this is not one of them. Right from the beginning I found my curiosity piqued and I was rooting for Joe Ledger even though I still didn't know too much about him. Jonathan Maberry does an excellent job of story telling in Patient Zero by the manner in which he reveals the bigger picture while at the same time providing increased insight into the man that is Joe Ledger. Patient Zero is a bit of a mash-up of 24 with a zombie apocalypse and things remain interesting from cover to cover.