In the third episode of the four-part story "Planet of Evil," the Doctor (
Tom Baker) and Sarah (Elisabeth Sladen) continue their efforts to prevent deadly anti-matter from the planet Zeta Minor from being unleashed in the Matter Universe. Their efforts are complicated by the duplicity of single-minded Moestran geologist Professor Sorenson (
Frederick Jaeger), not to mention a voracious anti-matter monster. Ultimately, the Doctor is forced to land on Zeta Minor, which act may result in his own grisly demise. Written by David Maloney, "Planet of Evil, Episode 3" was originally broadcast on October 11, 1975. ~ Hal Erickson, All Movie Guide