One of the rarest of the early Doctor Who series, with William Hartnell as the crusty old Doctor, Edge of Destruction is entirely based in the Tardis, which has stopped somewhere between worlds and times. The Doctor blames Ian and Barbara, the two teachers who came aboard in search for answers about his granddaughter, Susan, assuming they have committed sabotage in an attempt to return to their own time. They, in turn, in spite of recent shared escapes from Cavemen and Daleks, have no particular reason to trust his sanity. Something is causing one after another of them to act with violent irrationality, and the clock is ticking towards their destruction... This is a claustrophobic two-episode plot in which the series examines closely some of its more beloved assumptions. For example, who, in this situation, is good and who dangerous--the restriction to a single set may have started as an economy measure but virtue is made of necessity.Also included is the original pilot episode, An Unearthly Child, with several retakes. --Roz Kaveney