The Assassin's Mace is the second of a five-book series featuring FBI Special Agent Sean Roberts and the companion to Scimitar Strike. As the recently appointed deputy is acclimating to his new position, the FBI's Joint Terrorist Task Force (JTTF) is responding to back-to-back attacks on the nation's capital. The threat horizon is about to expand exponentially.

Following the death of Quds Force commander Qassem Soleimani, the Supreme Council for National Security of the Islamic Republic of Iran declared, "We will hold the United States responsible for the consequences of their criminal adventurism. The US shall learn the criminal attack against our beloved brother was the largest strategic mistake they could make. The consequences of this miscalculation will be devastating."

The declaration referred to thirteen revenge scenarios to avenge the death of the Quds Force general at the hands of the Americans. The dust had yet to settle from an assassination attempt against the Saudi Ambassador when Washington, DC, was again rocked by terrorism. An attack on the DC Metro has shut down the DC transportation system and shattered the confidence of the intelligence community. Meanwhile, Roberts and members of the JTTF are in a race against the clock to head off the most devastating of the scenarios--the Assassin's Mace.