Throw convention out the window if you’re planning on seeing “Terminator Genisys,” the fifth installment in the action franchise that made Arnold Schwarzenegger a household name.

Though it’s not completely necessary to have seen all four previous films, a working knowledge of James Cameron’s classics “The Terminator” and “Terminator 2: Judgement Day” will be handy, along with pencil and paper to keep track of all the alternate timelines.

While the original “Terminator” films (excluding the subpar “Rise of the Machines” and “Salvation” entries) operate in a closed loop universe based on singular time travel events, “Genisys” throws almost everything out the window.

For a while, this leads to some compelling action sequences, including Schwarzenegger fighting a younger, CGI-version of himself and the reappearance of the shape-shifting, liquid metal T-1000 Terminators.

Once the second time jump happens (and you may lose track of them all after a while), the plot folds in on itself for a disturbing and not entirely satisfying conclusion.

“Game of Thrones” actress Emilia Clarke shines in an otherwise bland film, acting wise, giving viewers a character worth rooting for as mother of the resistance Sarah Connor.

The stone-faced Jai Courtney, best known as Eric from the “Divergent” trilogy, muddles his way through a mediocre performance as “Terminator” mainstay Kyle Reese. While not totally ineffective, Courtney often sits third banana while Emilia Clarke and Schwarzenegger do all of the heavy lifting.

For all his warts as an actor, Schwarzenegger can’t miss as a Terminator — good or bad — and his overly robotic smile is one of the most genuinely humorous moments on screen so far this year.

As a whole, “Genisys” opts for glitz and glamour over a coherent story at every turn, as if writers Laeta Kalogridis and Patrick Lussier just turned to each other and said, “How can we top what just happened? Let’s flip a bus on the Golden Gate Bridge.”

As an aside, has anyone noticed that San Francisco and its illustrious bridge get decimated in action films more than any other city nowadays?

From last year’s “Godzilla” to “San Andreas” and “Genisys,” the city by the bay has been ruthlessly targeted again and again. Apparently, it’s also the main background for the destruction of upcoming films “Ant-Man” and “Pixels.” Where is the San Francisco Chamber of Commerce when you need them?

Turn your brain off when heading to the theaters for “Genisys,” which doesn’t quite offer the punch or pizazz “Jurassic World” does, but gives just enough hope for a brighter future.