: The Doctor takes a solo flight into space—without the TARDIS—to find the real astronauts aboard an alien mother ship.

: Michael Ferguson , noted for his use of lens flares and dynamic action sequences.

: Primarily credited to David Whitaker , though the final script was heavily rewritten by Malcolm Hulke , Trevor Ray , and Terrance Dicks .

: The Doctor and UNIT eventually thwart Carrington's broadcast plans and arrange a peaceful exchange: the ambassadors return home, and the human astronauts are released safely to Earth. Production & Cast

The story revolves around a mystery at regarding Mars Probe 7 , which has been out of contact for seven months.

: The kidnapping is orchestrated by General Carrington , a xenophobic ex-astronaut who intends to use the ambassadors to incite a war against their kind.