Air: May 9 1970. 7 eps.
UNIT has been assigned to oversee the production of a project called The Inferno, a massive drilling machine delving into the earth’s crust and retrieving a special substance. Unfortunately, this substance, if came in contact, turns anyone into savage, overheating Primords. After a disastrous experiment gone wrong with the Tardis’ console, The Doctor finds himself in a parallel world like his own. There the UNIT branch is cold-hearted and working on the same experiment as the one in his world. Once the experiment goes awry, can The Doctor make the right choice, to save this world, or to abandon this one and save his own? Liz leaves.