England, the near future. A strange anti-matter creature arrives on Earth and attacks UNIT HQ. It seems to be specifically seeking the Doctor out - but why? With the Time Lords themselves unable to help, it seems the only person who can help the Doctor is himself - or selves...
Elenco: William Hartnell , Patrick Troughton , Jon Pertwee , Tom Baker , Peter Davison , Colin Baker , Sylvester McCoy .