In the first episode of the six-part story "The Mutants," the Doctor (Jon Pertwee) and Jo (Katy Manning) are summoned to the 30th century, where they are ordered by the Time Lords to deliver a secret package to the planet Solos. The fact that the package contains some crucial bio-readings is but a prologue to the Doctor's latest assignment: To enable the primitive Solonians to begin their evolutionary process. But as can be gathered by the fact that there are more episodes to come, this will not be an easy task. Written by Bob Baker and David Martin, "The Mutants, Episode 1" first aired on April 8, 1972. ~ Hal Erickson, Rovi