In the first episode of the six-part story "The Chase," the Doctor (William Hartnell) decides to experiment with the space-time visualizer which he had obtained in the previous adventure "The Space Museum." In so doing, the Doctor makes a horrifying discovery: The dreaded mutant Daleks have created their own time machine and intend to use the device to destroy the TARDIS and its crew. This episode was written by Terry Nation, the man who originally created the Daleks as part and parcel of the overall Doctor Who saga. "The Chase" was first telecast on May 22, 1965. ~ Hal Erickson, Rovi