A fast-paced and exciting Star Trek adventure in which a new technology of clandestinely studying primitive peoples, mind-linking with them to share their psyches and knowledge, works to Spock's disadvantage. Spock is inadvertently linked to a megalomaniacal madman, is overwhelmed by the feedback, and takes over the planet, holding the Enterprise hostage in the process. An original concept, though the story is better handled for action than characterization. ( )