Captain Kirk finds himself haunted by guilt from his past as the fate of an alien world hangs in the balance. FAN NOTE: This episode involves original series character story lines: Rayna from "Requiem for Methuselah" (s3e19), Miramanee from "The Paradise Syndrome" (s3e03), and Edith Keeler from "The City on the Edge of Forever" (s1e28).