Our 50th Anniversary countdown concludes as Scott and Matt discuss the origins of the First Doctor with the very first William Hartnell 4-part serial “An Unearthly Child”. Two schoolteachers are concerned with the odd behavior of their student Susan and decide to follow her home. Who is Susan's mysterious grandfather known only as "The Doctor"? How can the abandoned police box Susan and the Doctor call home possibly be bigger on the inside? What exactly is a "TARDIS"? Find out in the latest episode of The Doctor's Companion! And remember, BEWARE OF SPOILERS!!

PLUS: "An Adventure in Space in Time"!!

Next: Matt Smith, David Tennant, John Hurt and "The Day of the Doctor"!! Plus, Tom Baker, Peter Davision, Colin Baker, Sylvester McCoy, and Paul McGann in the Big Finish Audio 50th Anniversary special "The Light at the End"!!