Hoping to increase Darrin's bank account and make life easier for Samantha, Endora casts an "ambition" spell on her son-in-law. As a result, Darrin becomes a greedy, power-mad backstabber -- and his boss, Larry Tate, suffers accordingly. Leon Ames makes a guest appearance as Larry's seldom-seen senior partner, Mr. McMann, with Jeanne Sorel as Mrs. McMann. Written by Lila Garrett and Bernie Kahn, "What Makes Darrin Run?" first aired on February 12, 1970. ~ Hal Erickson, Rovi