Killjoy (Alexa Vega) is a secondary villainess in Machette Kills. Machete Cortez (Danny Trejo) and Sartana Rivera (Jessica Alba) attempt to capture weapon dealers who have been supplying the Mexican drug cartels. The military men are then all killed by the gangsters, who in turn are wiped out by another intervening party. Its leader murders Sartana while Machete is arrested by corrupt Sheriff Doakes (William Sadler) and Deputy Clebourne (Samuel Davis). Doakes unsuccessfully tries to hang Machete but the President of the US, Rathcock (Charlie Sheen), intervenes. Machete is brought to the White House, where the president offers him US citizenship if he eliminates Marcos Mendez (Demián Bichir), a psychopath who is threatening to fire a nuclear missile at Washington, D.C. if the American government does not intervene to stop the rampant drug cartels in Mexico and the corruption of its government.
Machete agrees and travels to San Antonio, where he meets his handler Blanca Vasquez (Amber Heard), an undercover beauty pageant competitor. She sends him to Acapulco to meet a young woman, Cereza (Vanessa Hudgens), who can lead him to Mendez. Machete finds her in a brothel run by her mother, Madame Desdemona (Sofía Vergara), who attempts to kill Machete before he escapes with Cereza. She takes him to Mendez's associate, Zaror (Marko Zaror), who kills Cereza before taking Machete to Mendez's base of operations.
There, Machete learns that Mendez has wired the missile's launch device to Mendez' heart and triggered its launch in 24 hours. If he dies, the missile fires. After Machete kills Zaror, he also captures Mendez, intending to escort Mendez to US and find a way to disarm the missile. Machete learns that Mendez is an ex-secret agent who tried to expose his corrupt superiors, only to be betrayed and forced to watch his family being tortured. The trauma drove him insane, creating his split personalities and leading him to join forces with the missile's creator.
Shortly thereafter, a hit is put out on them. Machete is targeted by several assailants, including Madame Desdemona and her prostitute assassins including Killjoy (Alexa Vega) who pursue Machette in their van firing endless ammunition into Machettes armored covered vehicle who pops up the roof of his vehicle and throws a detonating machette in the hood of the van.The prostitute assassins all jump from the van in time before it crashes still firing.Machette gets away and that is the last we see of them.