In London in 1938, actress Julia Lambert is at her peak, physically and professionally, but her successful theatrical career and her marriage to handsome impresario Michael Gosselyn have become stale and unfulfilling. She longs for novelty, excitement, sparks. Enter Tom Fennell. A younger man who claims to be Julia's greatest fan. Finding his ardor irresistible, she decides that romance is the best antidote to a mid-life crisis and embarks on a passionate affair. Life becomes more daring and exciting, until Julia's young lover callously tries to relegate her to a supporting role. But on opening night, Julia reveals that she is a more formidable actress than anyone ever imagined.