Death Becomes Her (1992)

"In one small bottle... The fountain of youth. The secret of eternal life. The power of an ancient potion. Sometimes it works... sometimes it doesn't."

Madeline is married to Ernest, who was once her arch-rival Helen's fiancé. After recovering from a mental breakdown, Helen vows to kill Madeline and steal back Ernest. Unfortunately for everyone, the introduction of a magic potion causes things to be a great deal more complicated than a mere murder plot.