Brice Miller is a young Marine who has been fighting with the legendary 3rd Battalion, 5th Marines (nicknamed the “Darkhorse” battalion) in the deadly alleys of Iraq. Upon his units most recent return to Camp Pendleton from Iraq in 2008, he is awarded the Silver Star for gallantry on the battlefield, his third purple heart and an impressive, early promotion to gunnery sergeant. Though the young ‘gunny’ looks and acts like an invincible Marine, his outward appearance masks his dark, inner turmoil. He can’t sleep, experiences terrible flashbacks and he is uncertain about his future. Worst of all, he is haunted with an ever-present case of survivor’s guilt. Brice’s best friend, now a bedridden quadriplegic, incurred his devastating injury in Fallujah while on a mission he led in 2004.
Miller decides that the only way to rid himself of these guilty feelings and pervasive nightmares is to leave the Marine Corps. He submits his separation request to his company commander, who is also his mentor. His commander suggests another solution …professional counseling for his psychological issues and one month of leave to clear his head. Heeding his mentor’s advice, he meets with the base counselor and commences a month of long overdue leave. He first travels to the home of his adopted parents in West Texas and then to the bedside of his best friend, Bobby Ridger, who is being cared for at his parent’s family ranch located in a small Montana town. Coincidently, Ridger was also given the name of “Dark Horse” by his Arapahoe neighbors for an act of kindness he performed when he was a young boy.
Thus, opens the story of how Miller, his best friend and his company commander are drawn together to begin a very unusual journey. Their journey reaches its climax when they make one last stand together in an attempt to thwart a simple terrorist plot that should never have occurred. Bungling Washington politics, crooked state officials and bad cops in a small Montana town all contribute to the successful terrorist ambush, by ninety Al Qaeda terrorists, of over three hundred sixth grade students during their year-end field trip in Yellowstone National Park.