When newly married young woman Frances Aldridge loses her husband in a freak car accident, friends persuade her that a holiday in the United States would help her to recover her vitality. Deciding to travel by bus, she chooses a route which transverses the vast American landscape, from New York to Colorado. As she crosses the States she begins to fall in love with their splendour, and on the bus, she encounters many friendly people who share their stories, including Jim Field -- strangely enigmatic in this open country, handsome and travelling with a companion who she takes to be his mother. One night in Cleveland, Frances is woken abruptly in the middle of the night, by what she thinks is the door to her hotel room clicking shut. The next morning, she discovers that her pearl earrings are missing. She does not bother to report this minor theft, but is appalled to read in the news a few days later that an elderly woman had been murdered in the same hotel the very night she had been there. In the dramatic story that unfolds, Frances finds herself increasingly feeling as though she is being followed, state to state, city to city ...and murder to murder.