Hoping that Samantha will abandon Darrin in favor of her former warlock boyfriend, Rollo (Ron Randell), Endora creates a love potion for Sam. Unfortunately, Endora downs the potion herself and instantly falls head over heels in love with Darrin's loutish client, Bo Callahan (Arch Johnson). Of course, Samantha takes a hand in resolving this crisis of the heart. Scripted by James Henerson and Ed Jurist from a story by Henerson, "Once in a Vial" first aired on January 4, 1968. ~ Hal Erickson, Rovi