"The Friendly Killers" by S. M. Tenneshaw is a science fiction novel written in the late 1950s. The story revolves around Agent Mark Traynor, who is ensnared in a galactic conflict against an alien race known as the Kel, which has been infiltrating human defenses while masquerading as allies. As he races against time to uncover the truth behind the Kel's insidious plot, he grapples with a society that has been conditioned to suppress emotions and humanity. The opening of the book sets a tense stage for the unfolding drama. Mark Traynor arrives on the planet Rizal, where he is aware of the pressure from Controller Alfred Kruze to solve the mysteries of the Kel while battling potential reconditioning due to his unconditioned state. As he encounters various characters, including Controller Gaylord and the enigmatic Celeste Stelpa, who proves to have a history connected to the Kel, Traynor realizes that the stakes are far higher than anticipated. He must navigate a treacherous game of power, deception, and identity as he discovers that his mission is not only to save humanity but also to confront the emotional turmoil within himself, particularly regarding the impact of the thrill-mills—devices designed to heighten human experience beyond conditioned limits. (This is an automatically generated summary.)