Victor Papas is attacked at his home by two men and burned to death with a flamethrower, along with his girlfriend.
Shamus McCoy, a private detective in Brooklyn, New York, takes on the case after receiving a lucrative request from E.J. Hume, a wealthy businessman who runs a network of companies. The job is to recover diamonds that were stolen from Papas and to uncover who killed him. McCoy, attracted by the high fee, agrees and begins to investigate with the help of his friend Springy, [Larry Block], an informant, and a drug dealer he knows. The trio starts digging into Papas’ background and quickly uncovers that he and his girlfriend were connected to a company called River Edge Export.
According to Springy’s information, River Edge Export’s president is Felix Montaigne, a famous former football star who became a corporate executive, bought the company, and assumed control. Papas was also linked to Bolton, a bar bouncer at a place called the Health Club. McCoy tails Bolton, waits for the bar to close, and ambushes him, beating him to extract information. Bolton reveals that Felix Montaigne was the killer behind Papas’s death.
The next morning, McCoy visits Felix Montaigne’s luxurious apartment, where Alexis Montaigne appears. Alexis is Felix’s elder sister, and Felix admits that Papas and his girlfriend worked for River Edge Export, but he swears he does not know about their criminal activities. When asked about the source of the company’s funds, Felix hints at a partner but won’t disclose who it is.
A few days later, McCoy is ambushed by three thugs and warned to forget Papas. Alexis returns to McCoy’s place to ask him to investigate her brother Felix, whose behavior has become increasingly erratic. McCoy, who finds himself drawn to Alexis, agrees to take on the job.
The following day, McCoy sneaks into River Edge Export’s warehouse and discovers a hidden cache of weapons, including machine guns, and a dead man. He is discovered by a trio of assassins but manages to escape. He learns that Hume is the major shareholder of River Edge Export, and realizes this case is larger and more dangerous than he anticipated, so he tells Hume he cannot continue the investigation. He then visits Col. Craig C. Hardcore at the Army Weapons Depot, posing as a weapons dealer. The colonel’s illegal sales to River Edge Export come to light, but while the colonel explains the matter, he is shot and killed by two car-crash assailants, and McCoy barely escapes.
In a turn that confirms Bolton’s warning, Felix Montaigne is revealed to be Papas’s killer who stole the jewels. Hume had asked McCoy to look into Papas’s fate without realizing that Felix was the culprit. As the investigation deepens, Hume fears his own arms-smuggling operation will be exposed, and he sends a hitman to silence McCoy. Springy is killed by an unknown assassin, adding to the mounting danger.
McCoy crashes the high-society fortress of Hume, breaking into Hume’s mansion and confronting him. He is bitten by Hume’s ferocious dog and captured by Hume’s minions. In a tense room, he finds Felix, who has been beaten and is on the edge of death. As McCoy and Felix are taken outside, McCoy manages to escape, but Felix is fatally shot. McCoy then fights his way through Hume’s guards, subduing them one by one, and prevents Hume from escaping in a car. The arriving police close the net, and Hume is arrested, bringing a long, perilous case to a tense, decisive close.
