Miklo is brought to meet the head of La Onda by a fellow inmate, Popeye, who recognizes his gang tattoo from East Los Angeles. The Black Guerrilla Army is led by an inmate named Bonafide, the Aryan Vanguard is led by an inmate named Red Ryder, and La Onda is led by Montana. The prison is run by three gangs, all of whom are based on their racial backgrounds.

While in San Quentin, Miklo finds trouble adapting to prison life as his multi-ethnic heritage provides him with few allies in a racially-segregated penitentiary. narcotics detective after leaving the Marine Corps. His addiction leads to him being disowned by his family after his 12-year-old brother Juanito dies of an accidental overdose on Cruz's heroin supply.

He also becomes a heroin addict due to the recurring back pain. Their three paths diverge: Miklo is sent to San Quentin State Prison for violating his probation, Paco volunteers for military service in the United States Marine Corps as an alternative choice to prison, and Cruz continues his passion for art. They almost escape from the police, but while flicking them off, Paco crashes into another car at the El Pino tree, and the other Vatos Locos gang members escape before getting arrested, but Miklo and Paco are apprehended by the police and are arrested. However, Miklo has been shot by Spider before killing him and while Paco tries to get Miklo to the hospital, he and the other Vatos Locos end up being chased by the police. When Vatos Locos learn of the attack, they perform a well-planned counterattack ending dramatically with the murder of the rival gang's leader, 'Spider'. However, the Tres Puntos gang soon takes revenge by brutally attacking Cruz who is a budding artist, and damaging his back for life. His assault earns him a placa, a tattoo as a token of his membership in the Vatos Locos mate street gang. Miklo then proves himself worthy for the gang when he performs an attack on a rival gang, Tres Puntos. While talking to his cousin Cruz about getting into the gang, his other cousin Paco tells him that he can't because of the way he looks. On his return from Las Vegas, Nevada, Miklo visits his mother, then goes to stay with his two cousins Paco and Cruz. It has also earned him the nickname 'Milkweed.' However, his Caucasian appearance (fair skin, blond hair, and blue eyes) from his white father has made him less accepted among the people of El Pico Aliso barrio, where they have all grown up. Miklo Velka is a man of Mexican and Caucasian ethnicity who, before coming to live with his cousins, attacked his father.

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