A series of missions of the Enterprise, under the command of James T. Kirk: a rematch with Ies Breddell, who has a powerful new weapon capable of destroying the Federation; evidence of advanced technology on a stone-age planet; a reunion with the powerful Trelane, this time obsessed with World War I; a distress call from a barren world; Spock's abduction by mysterious forces as the Enterprise explores a dangerous rift in space; and terrorists seizing control of a museum with Kirk, Scotty and Checkov trapped inside. Through it all, a reclusive but advanced alien race is watching and testing the Enterprise, wondering if they should break their long silence and make contact with the Federation.