A deadly plague strikes America's cities. Hospital ERs are jammed, chaos reigns in the streets, people are dropping like flies. Someone has taken the war on drugs into their own hands and poisoned the narcotics supply. And the most chilling of all: the majority of Americans approve.

Summoned back to Washington by the director who exiled him, maverick FBI agent Mark Beamon is given the thankless task of discovering who's behind the full-page ads that have suddenly appeared in newspapers across the country, giving addicts a simple choice: Quit or die.

Teamed with a female field agent as icily analytical as he is intuitive, Beamon begins a desperate manhunt for the only mass murderer in history ever to win popular support. The race is on against the drug cartels, the Cosa Nostra, and the random violence on the streets as the poisoned drugs take their grim toll.

Agent Laura Vilechi wants to spread the net wide, across three continents, but Beamon's gut tells him to look closer to home. There is something eerily familiar about his ruthless adversary, reminding him of the coldest killer he ever encountered—not a criminal but a colleague in an interagency undercover operation. Could it be that this invisible enemy is the U.S. government itself?