When the TARDIS materializes just outside a sleepy English village, it appears the Doctor and Sarah Jane are nearly "home" at last.  But all is not as it seems in rural paradise.  White suited, gun wielding guards stalk the countryside, while the village itself is eerily deserted.  As the Doctor and Sarah look on, a UNIT member leaps over a cliff to his death and, as the clock strikes twelve, the local pub is suddenly filled with strangely robotic villagers.  The UNIT member is amongst them, very much alive.  What exactly is happening here?  The Doctor is mystified, setting off for UNIT HQ in search of the answers.  There, with the Brigadier away, Senior Defense Astronaut Guy Crayford holds court.  But just who is his shadowy master, the Thraal, Styggron?  Indeed, who are the Thraals and what have they got in store for the Earth?  Why has the TARDIS dematerialized seemingly of its own accord?   The Doctor must move quickly to find the truth, for the very future of mankind hangs in the balance…

• U.N.I.T. returns for this adventure, although without the Brigadier. 

• The Doctor's previous companion, Harry Sullivan, makes an appearance as does Sergeant Benton.

• "The Android Invasion" has also produced one of the all time Tom Baker quotes, "Is that finger loaded?"

• Milton Johns appears as "Guy Crayford.  His first appearance in Doctor Who was as the sadistic Benik in the Patrick Troughton story "The Enemy of the World."   His only other appearance was in the season 15 finale "The Invasion of Time."

• This story was written by Terry Nation (creator of the Daleks).  It is one of only two stories that he wrote for Doctor Who that didn't involve the Daleks.  The other story was "The Keys of Marinus."