Christopher spots four red cars in a row on his bus ride to school, making it a Good Day. Christopher explains that he ranks the day according to the number and color of the cars he sees on his way to school. Three red cars in a row isa Good Day, and five a Super Good Day. Four yellow cars in a row make it a Black Day. On Black Days Christopher refuses to speak to anyone and sits by himself at lunch. The school psychologist, Mr. Jeavons, points out that Christopher’s system surprises him since Christopher is so logical, but Christopher likes it and makes him feel safe. Christopher decides that he will set out once more to find Wellington’s killer because it is a Good Day.