Egypt 1099 CE, Qahira (Cairo)

Samuel, a Jewish doctor versed in alchemy, and Gregory, his English apprentice, are investigating a terrifying plague. The Nile has turned red with blood and fish are dying.

Near a small island, they wrangle a badly torn body from the jaws of a crocodile - but was this beast the killer? Samuel suspects foul play yet the authorities block his efforts to find the truth at every step. Ignoring the warnings from people in high places, and with nothing more to guide him than his scientific method, Samuel is determined to persist in his quest, especially after a series of gruesome murders seem to confirm his early suspicion.

Little does he know that the secret he will stumble on could shake the empire.

Assassins are on the prowl. A child is being hunted. Who finds him first will change the course of history.