It is a little known fact that the Tracy dynasty began with a broken paving stone. If Sarah Creighton-Ward had not tripped over a cracked paving stone that spring day in the year 2037, she would not have sent handsome young astronaut Jeff Tracy sprawling on the dirty London streets. Then she would never, by way of an apology, invited him to her engagement party, and he would never have met her fiancee's sister, Elizabeth. As she did trip, Jeff and Elizabeth met, fell in love and were married six months later. "What about that girl?" teased her husband. Elizabeth was indignant.