In Passion for Life: Psychology and the Human Spirit, John James and Muriel James state: "A universal hunger pervades the world. It is the hunger to get more out of life, to give more back, to be more involved, and to find more meaning." This hunger of the soul is vividly and imaginatively expressed in Lawrence Kasdan's Grand Canyon.
Mack (Kevin Kline) is an immigration lawyer who lives in Los Angeles with his wife Claire (Mary McDonnell) and his teenage son Roberto (Jeremy Sisto). He comes face-to-face with his own mortality when his car breaks down in a dangerous part of the city and he is approached by a threatening gang of black youths. A tow truck driver, Simon (Danny Glover), arrives just in the nick of time and defuses the situation.
Simon is a caring soul who keeps in constant touch with his deaf daughter in Washington, D.C., and looks after his sister who lives in a violence-ridden ghetto. Her teenage son is convinced that he will not live to be 25.
Meanwhile, Claire is out jogging one day when she hears a child crying in the bushes. She takes the abandoned baby home and informs her husband that the child needs a new mother.
Mack's best friend Davis (Steve Martin) is a producer of violent movies. He is shot by a thief who wants his Rolex watch. After briefly deciding that he should make less brutal movies, Davis goes back to his old ways. However, his life is changed by all the attention given to Claire and Mack's decision-making about the baby.
Mack initiates a friendship with Simon and tries to repay him for saving his life by finding his sister a better place to live. Then, after meeting Jane (Alfre Woodard), a friend of his secretary Dee (Mary-Louise Parker), Mack fixes her up on a date with Simon.
Lawrence Kasdan, who wrote the screenplay with his wife Meg, sees Grand Canyon as related to his earlier work The Big Chill about a group of baby boomers. Both dramas revolve around the question: Am I doing the right thing? As the characters connect, interact, and influence each other, new possibilities are born. Gradually, the future begins to look different.