Tread Perilously celebrates the fiftieth anniversary of Star Trek's debut with a look at the final episode of the original series: "Turnabout Intruder."

When a bitter scientist leaps into Kirk's body, it's up to Spock and McCoy to determine why the captain is acting so strange. When Spock discovers the truth, he is charged with mutiny as the scientist continues to lose her grip on command of the Enterprise. Meanwhile, William Shatner gets an opportunity to act his heart out.

Erik and Justin discuss the institutional sexism on display as the episode seems to outline -- with gusto -- why there are no female captains in the 2260s. Guest actor Sandra Smith gets high marks for her performance as Kirk while Shatner takes the opportunity to do some master class Shatnering. Justin invokes Just One of the Guys to illustrate an important point the story ignores and both he and Erik theorize why Nichelle Nichols is missing from the episode.