"Control Group" by Roger D. Aycock is a science fiction novella written during the late 1950s. The story follows a crew from the Terran Reclamations as they investigate an enigmatic planet, Alphard Six, previously occupied by the alien Hymenops. The plot hinges on the crew's attempts to understand the nature of inhabitants who appear to have descended from an ancient Terran expedition but are lost in time, surrounded by the implications of alien control and misunderstanding. The narrative primarily follows Navigator Farrell and his colleagues Stryker and Gibson as they explore this seemingly abandoned world. Initially, they encounter hostility, leading to an unexpected crash. Captured and later freed, they learn that the current inhabitants are descendants of a human crew conditioned by the Hymenops to believe they are from an original Terran colony. Throughout their investigation, the crew grapples with uncertainties about alien motivations and the consequences of human adaptation over generations. Ultimately, the story culminates in a revelation of identity and purpose, expressing themes of survival, adaptation, and the complexities of colonization and coexistence across time and cultures. (This is an automatically generated summary.)