Lieutenant Colonel Tyler Graven is a certified genius known as the "Demon of Kyoto" and he specializes in death.When an assassin attempts to kill pharmaceutical mogul Mortimer Sackler, Tyler becomes the lead suspect and the target of a $100 million dollar hit. To save himself and clear his name, he must hunt down the true killer, a deadly entity known only as The Priest.Tyler teams up with his former military unit, The Four Horseman, including his brother, crack-shot Corporal Jack Graven, the mysterious Lance Corporal Jin Xialong, and his one-time flame Colonel Diana Levitas. Once, they were an elite fighting team known for completing two of the most successful campaigns against terrorism ever launched. Now, they'll find themselves locked in a war with The Church, the most influential organization on the planet--and pitted against the supernatural forces of the Underworld itself.During their mission, Tyler and Jack learn of the legendary Black Muramasa, the Immortal Ending Blade, the only weapon that can destroy immortals such as demons, angels, vampires, seraphim, and nephilim. As they uncover the secrets of the ancient black blade--and their own heritage--they are faced with unforetold powers and infinite evils. If the Four Horsemen succeed, they may save themselves. If they fail, it'll cost them their sanity, their lives, and even their souls. . .Here comes an action-packed, gun-slinging fantasy adventure that packs the punch of a military thriller combined with high-stakes supernatural intrigue.