In the early 1970's, in the U.S., Dr. Alexis Dawson , his younger brother Abraham, and Eddy Frederick discovered a drug called "Banana Fish". It is potentially the perfect mind-control weapon, but in early incarnations it mainly renders its victims insane or suicidal.
This story starts in South Vietnam, 1973. Griffin suddenly begins firing at his fellow GIs. Max Lobo shoots him to stop him from firing. Griffin is out of his mind and can only say "Banana Fish".
The story jumps to New York, in 1985. Ash Lynx, a street kids leader, comes across a man who is shot and dying. The man hands Ash a locket and says "Los Angeles Westwood 42....... See Banana Fish". Ash goes home and asks his elder brother Griffin, who has become a human vegetable, what Banana Fish is.
Dino Gorzine, who is a homosexual Corsican Mafia boss and loves Ash, is also interested in Banana Fish.
Eiji Okumura comes from Japan with Shun-ichi Ibe, a photographer. They meet Ash to take street kids' photos.
Dino frames Ash and he is sent to a prison. Ash meets Max Lobo there. While Ash is in prison, Griffin is killed by Dino's henchmen.
Later, Ash is released from prison and attempts to kill Dino with the help of his friend Shorter, but they fail and escape.
Ash, Shorter, Max, Eiji and Ibe visits Los Angeles Westwood 42. There they find Dr. Dawson's house. Dr. Dawson is out and they only meet his adopted son Yousiss, a Chinese American. Ash secretly accesses Dr. Dawson's computer to find out what Banana Fish is. Max receives a phone from his wife. She states their house was burgled. Ash and Max leave Dr. Dawson's house and rush to Max's wife's aid. Max's son says the burglars were Asians.
Yousiss actually is Li Yuelong, the youngest brother of a Chinese mafia family. He forcibly takes Eiji and Shorter to Gorzine's place. Ash and Max visit Gorzine to save them. Gorzine injects Banana Fish into Shorter and tells him to kill Eiji. Ash shoots and kills Shorter.
Ash and Eiji go back to New York. Ash accesses Gorzine's bank accounts using a computer and steals his money. That causes the Corsican foundation to lose money and Gorzine leaves the U.S.
Ash decides to challenge Frederick Ausser, another gang leader. They fight in the subway. Ash wins but is seriously injured and is taken to hospital by the police. The TV news states that he had been moved to the National Mental Health Center and died there. Eiji doesn't believe the news.
Ash meets Dr. Alexis Dawson in the National Mental Health Center and escapes with him. Ash studies in the library and speculates that Banana Fish is a drug synthecized from an Alkaroid plant.
Dino and Yuelong employ Blanca. He is the one who taught Ash fighting techniques. Dino and Yuelong threaten Ash and say that they will kill Eiji unless Ash hands over Dr. Dawson and all the report about Banana Fish to them. Also, Ash must live with Gorzine and become his successor. Ash feels that he has no option.
Eiji saves Ash from Gorzine's place with the help of Shin Su Lin, a Chinese-American gang leader, and Cane, an African-American gang leader.
Dino employs Colonel Fox ( who used to be a member of the French Foreign Legion) to destroy Ash's gang and it's new associates.
Ash's gang forms alliances with Chinese and African-American groups to fight against Gorzine and Yuelong. Yuelong wants to kill Eiji. One of the Chinese members shoots Eiji and he is taken to hospital.
After seeing Eiji at the hospital, Ash fights against Yuelong and Gorzine at the National Mental Health Center. Gorzine dies.
Eiji has to leave for Japan. Ash decides not to see him again. However, when he reads Eiji's letter he starts running to the airport. He is stabbed on his way to the airport.