Major Lex Kearney becomes the North's first counterespionage agent as he tries to discover who's behind the theft of Union cavalry horses in Colorado during the Civil War.

Major Lex Kearney, dishonorably discharged from the army for cowardice in battle, has actually volunteered to go undercover to try to prevent raids against shipments of horses desperately needed for the Union war effort. Falling in with the gang of jayhawkers and Confederate soldiers who have been conducting the raids, he gradually gains their trust and is put in a position where he can discover who has been giving them secret information revealing the routes of the horse shipments.—Doug Sederberg <[email protected]>