Any movie plot that hangs on the ability of an adult character to journey into the past to give vital advice to himself as a child is bound to register as somewhat convoluted.

Still, the riddles of time travel are not really the point of “Terminator: Genisys” (Paramount). The primary purpose of this easily forgotten latest chapter of the long-lasting sci-fi franchise is, rather, to empower its cast to blow things up, fire off weapons and drive with abandon.

What’s behind all this stylized ruckus? The post-apocalyptic conflict between murderous machines and embattled humanity in the world of 2029, that’s what.

The prospects of those fighting on the flesh-and-blood side are looking up, thanks to the work of their Messiah-like leader, John Connor (Jason Clarke). Just as he’s about to achieve a definitive victory, however, John faces a unique threat.

His adversaries, we learn, have used a time machine to send a cyborg (Byung-hun Lee) into the past to eliminate John’s mother, Sarah (Emilia Clarke), before she can give birth to him. Not to be outdone, John, in turn, dispatches Kyle Reese (Jai Courtney), his most trusted lieutenant, to follow the assassin back in time and protect Sarah.

Once safely arrived in the Reagan era, however, Kyle is confused to find that Sarah is already being shielded by another chronology-defying robot (Schwarzenegger) who seems to be fighting on the wrong side.

And then there’s grown-up Reece’s counsel-bearing encounter with little Reece.

Despite its relentlessness, the destruction on view carries with it little bloodshed. And the fact that time machine passengers can only be transported in the buff also is treated more as an occasion for smirking jokes than for visual exploitation. Together with the relative absence of obscenity in the dialogue, such restraint may lead at least some parents to consider “Terminator: Genisys” acceptable for mature teens.

The film contains pervasive action violence with minimal gore, several scenes of partial nudity, a few uses of profanity, at least one rough term and occasional crude and crass language. (A-III, PG-13).