Victor Kiley, a wanted fugitive, barely escapes after lawmen attempt to take him and an accomplice into custody. Kiley abducts a woman and her 16-year-old son as he tries to stay one step ahead of law enforcement, led by the FBI. Erskine leads the FBI's manhunt for Kiley, aware the wanted man has forced the woman and her son to accompany him. Erskine gambles with his own life to ensure the wanted man is taken into custody.
The bureau investigates the shooting of a ranch foreman in a border town. The main suspect is the sheriff that the agents have to work with. The sheriff was feuding with the powerful ranch owner whom the foreman worked for, as he was investigating him for transporting illegal aliens across the border.
An aging thief, assisted by younger accomplices, steals a 31-karat, legendary diamond. The plan goes awry almost immediately when one of the accomplices wounds himself with a pistol belonging to the jewel's owner. The remaining thieves don't trust each other. Erskine and Colby oversee a multi-state manhunt, trying to cut off any way the thieves can either fence, cut or ransom the large diamond. Before the case concludes, much treachery will unfold.
A spy ring is under investigation in the U.S. Matt Bernhardt is a member of the ring and when he is apprehended his nephew is wounded. Erskine goes undercover as the nephew and his investigation leads him to West Berlin and a plot to get the ring leader's wife out of the east sector.
In Detroit, ambitious Scott Rogers is about to set up an illegal casino backed by the Cosa Nostra. But Rogers wants more -- he is seeking to be admitted as a Cosa Nostra member. Rogers bribes syndicate member Martin Rawl $50,000 to sponsor him. At the same time, a former business partner of Rogers threatens to go to the authorities. The ex-business partner is shot. Erskine and Colby lead the FBI's investigation into the matter. The bureau intercepts a shipment of gambling equipment. Now, Cosa Nostra family leader Nolan Crist decides to cut Rogers off from further ...
Mary Ann Lowe is a teenage girl en route to a summer job as a camp counselor when she is kidnapped by a trio of kidnappers. They hold her in an isolated cabin in the mountains while contacting her parents for ransom money. She is the daughter of a wealthy Washington DC business man who also happens to be a good friend of Arthur Ward. While tracing Mary Ann's schedule suspicion falls on the hair salon and the woman who does her hair.
Two half-brothers fight for control of a Cosa Nostra family. The conflict is coming to a head as the Cosa Nostra Commission has scheduled a meeting in Chicago. A woman in love with one of the half-brothers is seized as leverage. The case is so important to the FBI that Assistant Director Arthur Ward joins Inspector Lewis Erskine and Special Agent Tom Colby as a bureau team of agents converges on O'Hare Airport. For the FBI team, the question is whether the Cosa Nostra members can be arrested without causing harm to the public.
A successful fence wants to leave his criminal life behind but is pressured after a major heist. Tom Colby is sent undercover but his life is in jeopardy when the gang suspect he's a lawman. Lewis Erskine also goes undercover despite the risks and an injury to Colby.
Four kidnappers by mistake abduct the sister of their intended victim. Erskine and Colby try to make sense of the botched crime. Erskine will risk his own life, taking the place of the kidnapped woman's husband who has been instructed to deliver the ransom. Meanwhile, one of the kidnappers is unstable and intends to take charge of the group.
Walker Graham Carr escapes from a mental hospital. He has been convicted of the murder of his wife but he is convinced she's still alive. Erskine and Colby lead the FBI's manhunt for Carr. Carr's uncertain mental condition complicates the bureau's search.
Erskine and Colby pursue a pair of bank robbers from Philadelphia to Oregon. The criminals, Perry and Shep, are an odd mix of urban and rural backgrounds. Perry plans the robberies while Shep (a "redneck" as Perry calls him) specializes in gun play. Their eventual target is the payroll of a tunnel construction project in Oregon. Along the way, Shep is drawn to a woman, who tries to play the criminals off each other. Shep also is a bit of ticking bomb. The FBI agents try to catch the criminals before fatalities occur.
A Boston company that is developing a new type of laser is the target of a spy ring. One compromised employee is injured at a cheap hotel when the elevator cable snaps. Erskine and Colby are assigned to protect the project. Meanwhile, the spy ring is targeting another employee, who is deep in debt, to entice him to provide the information the ring needs.
A man working for La Cosa Nostra is on trial. The man who recruited him into the criminal organization believes he will crack during the trial and arranges for him to jump bail and flee the country. Erskine and Colby lead the FBI's pursuit; the man's testimony is needed to incriminate La Cosa Nostra members. Meanwhile, the commission of La Cosa Nostra wants the man dead and has ordered a hit. On top of all that, the fleeing man's wife, who is seven months pregnant, is with him and her condition threatens her life and her unborn child's.
Erskine and Colby lead the manhunt for escaped prisoner Arthur McBride. McBride is a genius and a ruthless, borderline psychopath and more than willing to kill to accomplish his means. The FBI men will follow a trail from Kansas to Chicago to Miami. The question is whether Erskine can corner his quarry before his next big job: robbing an armored car on its way from a race track.
The mentally unstable Walker Oborn has abducted Emily Willis. FBI Assistant Director Arthur Ward tells Erskine that "the director" has taken a special interest in the case and wants it resolved as soon as possible. Erskine and Colby spearhead the FBI's search in the Pacific Northwest to bring the captured Emily home safely.
A group of young extremists wants to start the 'Revolution'. They blow up a govt. building but an anonymous caller phones in a tip to the police. Their leader believes someone connected to the group made the call. Because govt. property is destroyed the F.B.I. is called in to investigate.
The son of a wealthy but separated, couple is kidnapped. The abductors are a couple with issues: the man is an alcoholic while the woman is near the end of her endurance in dealing with her husband. On top of all that, the kidnapped boy has become seriously sick. Erskine and Colby lead the bureau's manhunt. But, with the boy's condition worsening, the question is whether they can break the case in time.
In Los Angeles, La Cosa Nostra has mounted an effort to infiltrate businesses owned by African Americans. Erskine and Colby lead the FBI's investigation. One businessman already has been left severely beaten when the FBI men enter the case.
Erskine and Colby are on the trail of a con artist who targets lonely, wealthy women. The FBI has entered the case because the man's latest technique involved impersonating a U.S. Navy officer. The man also is suspected of killing one of his victims. As a result, the FBI men have extra incentive to apprehend the man quickly.
Erskine and Colby seek to apprehend Arthur Majors, a fugitive who is now part of a Los Angeles-based drug ring. Majors and three others shot two and seriously wounded U.S. border patrol officers in Arizona while transporting drugs. Now, Majors has gone into business for himself. The FBI is in competition with syndicate hitmen to get to Majors first. The life of a young woman, who is fascinated by Majors, is now at risk as the hitmen close in on Majors.
The economics minister of an iron curtain country has defected. His daughter Maria is touring the U.S. and the FBI must get to her before a communist spy can spirit her back to her country to be held as ransom for her father.