Tom Haley, a rookie college teacher, is awakened by someone fiddling with his front door. Rushing downstairs, he sees a man hurrying down the street with a pronounced limp. The following day, he looks around Pulaski Avenue on his old red bicycle. He stops at the flats, a string of flat-roofed attached houses, where he meets Marcie Flann, a sensual waitress at the Prima Diner. Despite differences in background and outlook, the two begin dating.
In the meantime, Tom helps the local police solve a rash of burglaries in the area. Through patient sleuthing, he learns the prowler's name - Ron Luco, where he grew up and had gone to school. He also discovers that Marcie was Luco's former girlfriend. A local jewelry store heist is linked to Luco, but through intimidation and an alibi, he is acquitted.
Later, Marcie is disturbed by someone walking on her roof. By the time Tom arrives, the elusive culprit is gone. The plot turns, as Tom finds himself under surveillance by the relentless Luco, who carries a handgun. Amidst a stickball game at local schoolyard, Luco shows up - threatening Tom and Marcie with a gun. The narrative is interspersed with thumbnail sketches on racism, antisemitism, sports, infectious diseases, nuclear energy, algebra, statistics, history, poetry, immigration, and philosophy.