The Edge of Destruction

This story is the only classic series serial to be set entirely in the TARDIS set featuring only the Doctor and his companions. It's an interesting story to watch, purely because of it's strange plot and the interactions between the Doctor and Ian and Barbara. In this two-episode serial, something's going wrong with the TARDIS and tempers fly as no one knows who or what is to blame. Because there are no other characters or sets, to survive, The Edge of Destruction has to draw viewers in with an intriguing plot and great dialogue, and it does just that.

Perhaps it isn't the best story to watch if you're a fan of extravagant epics and otherworldly creatures but if you're looking to see an important story in Doctor Who's history, then look no further. Many important things are revealed about the TARDIS, including how it's food machine works and where everybody sleeps, and the relationships between the Doctor and his companions mellows from being a distrusting relationship into a lighthearted trustworthy relationship.