The Key of Skeleton Peak

Dark magic meets the Old West in The Key of Skeleton Peak: Legends of the Lost Causes, the epic conclusion to the action-adventure series!
Keech Blackwood and his fellow Lost Causes have won their share of battles, but the war against the forces of darkness still rages on.
In their final standoff against the ruthless outlaw and sorcerer, Reverend Rose, the Lost Causes face their most perilous trial yet: stopping Rose and his henchmen from retrieving the ancient, powerful objects that would return him to his full, frightening strength. As the vigilante orphans race to the dangerous depths of Skeleton Peak, the site of the Key that would free the Reverend from his wicked prison, they'll have to outmaneuver Rose's most faithful—and menacing—ally: a creature spawned by darkness and shadow. But ever in pursuit of justice and vengeance for their fallen families, the Lost Causes won't give up without a fight.
Packed with rip-roaring action, adventure, and powerful friendships, this series is perfect for fans of John Flanagan's The Brotherband Chronicles and Peter Lerangis's The Seven Wonders.
Praise for the Legends of the Lost Causes series:

"This is a fun and exciting story, written with the utmost respect for the Osage culture." —Wah-Zah-Zhi Cultural Center