The Doctor has vanished without a trace.  As per the Doctors instructions; the TARDIS has traveled to various points of earth's history and picked up several humans.   None of these humans are known to the friends, or companions of the Doctor, yet in a way they are the most important.  These are Companions that fell between the cracks.  Their history with the Doctor's incarnations are unknown, even to them.  But only they have the abilities, skills, and technology to continue the Doctor's work until they are able to find them.  But can a bunch of humans have such an effect of the universe…only time will tell.

Doctor Who: Between The Cracks

Gamer_Geekus_Alpha Series 8 title sequence logo