Changelings is set in a future where whole species have died leaving man on the edge of extinction, in a world filled with day walkers and night stalkers. The Director of the Changeling Program is firmly committed to a quest for the reconstruction of the DNA of live creatures, which results in physical shape changing of the still living. into new creatures called changelings. The ability to shape shift plays a large part in the scientific efforts to enhance the human race, turning criminals and threats to society into socially viable changelings; but also some more sinister characteristics are developed at the same time. The changed and the unchanged; and then there is the mighty Cerberus to contend with along Keanos and the ancient one, Thanatos. Enter crypto-biologist, Mike Caldwell, gifted in writing the codes necessary to produce effective changes for enhanced changelings Suspicious of Mike's motives, the Director assigns a companion to watch over him, but when his companion suddenly vanishes, Mike begins to question everything around him, and the fragile balance of this dying world is tipped to its limit.