Secret Agent X was one of the most lurid of pulp magazines, as these three novels reprinted from its pages prove. The series was unique in another respect. As a Wikipedia entry notes: "In the stories, the true identity of Secret Agent X is never revealed. He is a master of disguise, known as "the man of a thousand faces", who adopts several different identities in each story. Although he is a dedicated crime-fighter working undercover for the U.S. government, this is unknown to the police who consider him an outlaw. His true role is known only to newspaper reporter Betty Dale and his mysterious Washington controller, K-9."
Like other pulp hero novels, the Secret Agent X stories are filled with nonstop action, bizarre villains, fiendish weapons, and diabolical plots, as these book-length reprints show. If you love the Shadow, the Spider and Doc Savage, you will love Secret Agent X.