There are many places that most of us can never see: places that are sheltered, locked away, cordoned off from the outside world. But to the Doctor, and those who travel with him in his TARDIS, there is no such thing as a locked door. Anywhere in space and time is open to them to visit — even if sometimes it might be better to leave such places well alone. Section One, Flight, comprises four tales of travellers who left their homes for far-away destinations — to explore, to start a new life, or to fight for the survival of their species.