Special Agent Marcus Williams and his serial killer sibling, Francis Ackerman Jr., are on the trail of not just a single murderer, but an entire network of killers for hire. The trail of bodies leads them to San Francisco and a killer going by the codename Gladiator. Their target is working for a ruthless and reclusive syndicate leader, helping to expand the crime lord's territories through blood. But the Gladiator's machinations go much deeper than contract killing. Considering himself to be a modern-day Genghis Khan, the Gladiator has a plan to forever carve his name onto the evolution of mankind. To stop him, Ackerman, Marcus, and the team must plumb the depths of human depravity by diving into the worlds of organized crime, human trafficking, and underground bloodsports. The Gladiator is undefeated in his arena of death, but he's also never faced an opponent like Ackerman.