Unnatural and stilted conversation is the most irritating fault of this newest story about ranches and ranch life. Perhaps this is exaggerated because this experienced writer has this time failed to establish the levels of relationship between the brother and sister in her story. Ben is 20, his sister is 15 -- and neither seems right for the ages indicated. The story is exciting in spots. Cattle thieves are attacking the quiet western valley, and Ben organizes a prairie patrol to catch them. Ann does her share in finally bringing them to justice. A cowboy on their ranch, a suspect, turns out to be a secret service man. The plot seems contrived; the characterization weak. Disappointing.