The Cactus League presents stories from multiple narrators in Scottsdale, Arizona, the home of Salt River Fields, the spring training facility of the Los Angeles Lions professional baseball team.

Although he appears to be very straight-laced and respectable to outsiders, over the course of the novel it is revealed that Jason has recently been divorced by his wife and lost the vast majority of his wealth due to a serious gambling addiction.

The book opens with Michael and his wife returning to their Arizona house for the start of spring training, only to find that squatters have broken into it during the off-season.

The second chapter focuses on Tamara Rowland, a middle-aged divorcée who attempts to engage baseball players in casual sexual experiences each spring training season.

Chapter seven features two primary narrators: Lester Morrow, an aging musician who plays the stadium's organ, and William Goslin, a Lions first-round draft pick who showed great potential during his amateur career at his home in New Jersey, but is struggling to adjust to professional baseball.

The eighth chapter is about a six-year-old boy named Alex, whose mother is a drug addict who has been squatting in various houses, including Michael Taylor's earlier in the novel.

After paying the loan shark with the money he borrowed from William, the book ends with Jason returning to the stadium and finding an unconscious Alex in the back of the car.