A retired CIA operative, Paul Shepherdson, is pulled back into action when a U.S. senator is assassinated in a manner reminiscent of a notorious Soviet assassin known as Cassius. The FBI enlists the help of young analyst Ben Geary, who wrote his thesis on Cassius, to solve the case. Initially skeptical, Shepherdson is forced to work with Geary and discovers the possibility that Cassius might be alive and active once again. Their investigation leads them through a tangled web of espionage, old Cold War rivalries, and brutal killings.

As Shepherdson and Geary dig deeper, they uncover shocking revelations that challenge their perceptions of loyalty and betrayal. The stakes rise when they realize that Cassius’s mission may be far from over, and their own lives are in immediate danger. The investigation tests their limits, intelligence, and trust in each other as they race against time to prevent further bloodshed. In the unfolding series of events, motives and identities blur, keeping both the characters and the audience on edge until the final, unexpected twists come to light.