From the Introduction:
The waters receded and the animals were released to return to their own homes. Not all of them left unchanged however. Some bore Noah's Mark. As Noah had preserved them, now these animals were charged with protecting Man.
The mark has continued, with some animals of each kind being born with the Mark ever since. They are smarter than normal animals and they seek out others of their kind. Sometimes they find them in their own species, other times they find different animals with the Mark.
It has been a long time since the first animals bore the Mark and in that time things have changed for both man and the animals. The world is a very different place than it was in the time of Noah. Some of those who bear the Mark have come to believe that Man cannot be saved without returning him to the technology of Noah's time. Others have different ideas of what it mean to protect man and even whom man is being protected from.
For those who call themselves the True, their role has expanded. In the beginning they sought only to protect Man from himself. Where greed and evil took hold, the True worked to remove those men who did evil things and thus protect others from their crimes. In the times since, they've been forced to add protection from those who bear the Mark and seek to use their power to protect Man in other ways. Sometimes the False, as they are collectively known, work against the interests of normal men. In those cases, the True must strive against them.