The planet Frontios, in the distant future. Following Earth's destruction, a tiny colony struggles to eke out a life on this desolate world. But where do the bombardments that threaten them originate from? Little does the Doctor suspect that somewhere nearby lurks a power capable of ripping even the TARDIS apart...
Elenco: William Hartnell , Patrick Troughton , Jon Pertwee , Tom Baker , Peter Davison , Colin Baker , Sylvester McCoy .