Elizabeth Montgomery appears in the dual role of wifely witch Samantha Stephens and her flamboyant lookalike cousin Serena. Goaded on by Endora, Serena does her best to break up Sam's marriage to Darrin. It is all part of a master plan to force Sam to give up her mortal existence and devote all her time to her new responsibilities as Queen of the Witches, but as always, Sam has the last laugh on Endora. Written by Ed Jurist, "Double, Double, Toil and Trouble" was originally scheduled to air on September 28, 1967, but was moved up a week to October 5. ~ Hal Erickson, Rovi