Machete don’t tweet. Machete don’t smoke. Machete mostly speaks in terse sentences, mostly on the subject of what Machete don’t do. Machete Cortez, of course, is the grim-faced Mexican vengeance machine played by Danny Trejo, in the mold of Billy Jack and Sweet Sweetback, in director Robert Rodriguez’s “Machete Kills,” the second of a planned trilogy that pays homage to grindhouse schlock from the 1970s.

Giddily unsophisticated and punctuated with frequent bursts of comic violence, the second installment does honor to the franchise. In the universe of Machete, the merest feint in the direction of plausibility is in bad taste. Not only must bullets miss Machete, but they must be fired at point-blank range from can’t-miss angles. Even the rare bullet that finds its mark doesn’t leave a scar.

The political overtones of the first “Machete” film, which lionized a network of migrant smugglers, are mostly gone. Machete himself, a former federal agent in Mexico, is now freelancing for a U.S. border agency, and early in the film he is trying to stop a rogue military unit from selling heavy weapons to a drug cartel. The deal goes south, and so must Machete, on the trail of a weapon of mass destruction that has fallen into the hands of Mendez (Demian Bechir), a revolutionary who is threatening a strike against the U.S.

The movie opens with Machete getting an assignment from the U.S. president (Charlie Sheen, hilariously billed as Carlos Estevez in the credits) to abduct Mendez and bring him back to American soil. Let’s just say that this doesn’t go quite as planned, and the movie shifts into quite a different realm. There is no point in spoiling the surprise, although Mr. Rodriguez does exactly this by opening “Machete Kills” with a fake trailer that advertises the third Machete movie.

Michelle Rodriguez returns as Luz, the leader of the shadowy “network” that supports Machete’s activities. Jessica Alba is also back from the first movie as federal agent Sartana Rivera. But there are some welcome newcomers to the series. An assassin known only as El Chameleon, who wants to collect the bounty on Machete and Mendez, is able to alter his appearance at will and is played by four quite different actors. Mel Gibson stretches himself in the role of a megalomaniacal tycoon and cult leader looking to change the course of human history.

For those who want to wallow in the shallows of this gory, self-referential splatterfest, “Machete Kills” delivers death by speedboat propeller, helicopter rotor, bustier-mounted Gatlin gun, a molecular disrupter pistol that turns people inside-out, and of course multiple decapitations delivered by precision machete strokes. Mr. Rodriguez is stretching to extend the Machete joke into a second film, but it turns out to be funnier than the first one. The jokes are bigger, and the action sequences are bolder. Despite a second act that lags a bit, “Machete Kills” should satisfy the bloodlust of its target audience.

 ★★½ 

TITLE: “Machete Kills”

CREDITS: Directed by Robert Rodriguez; screenplay by Kyle Ward

RATING: R for frequent decapitations, sexually charged violence and crude language

RUNNING TIME: 107 minutes

MAXIMUM RATING: FOUR STARS