Another ‘Transformers’ movie is about to hit theaters. Do U.S. moviegoers care?

Paramount Pictures has retooled its decade-old “Transformers” franchise with a new mythology that ties the giant alien robots to the legend of King Arthur, Stonehenge and World War II. Still, after four previous movies, the Michael Bay franchise may be looking rusty to American audiences.

The fifth in the series, “Transformers: The Last Knight,” should gross $70 million Wednesday through Sunday in the United States and Canada, according to people who have reviewed audience surveys. Though that number will almost certainly be enough to unseat “Cars 3” from the No. 1 chart position, it will represent a steep drop from the previous installment. “Transformers: Age of Extinction,” released in 2014, opened with $100 million in its first three days.

The domestic slowdown means Paramount is looking more than ever to foreign grosses, especially in China, to keep the robots-in-disguise in working condition.

More sequel fatigue?

Since the first “Transformers” in 2007, the series based on the Hasbro toys and 1980s cartoon has become Paramount’s most dependable franchise, grossing about $3.8 billion over the course of four films, all directed by Bay. So, it’s easy to see why Paramount set up a writers room of more than a dozen scribes to build out an expanded “cinematic universe” for the characters. Hey, it’s working for Marvel.

To raise the stakes for “The Last Knight,” which stars Mark Wahlberg as hero Cade Yeager and Anthony Hopkins as an English lord, Bay and his team used new camera rigs to film in Imax 3-D, and built a giant replica of Stonehenge.

But “Transformers” may become the latest movie to suffer the fate of other recent summer reboots, remakes and sequels that audiences weren’t clamoring for, at least in the United States. Would-be blockbusters, including “Baywatch,” “Alien: Covenant” and “The Mummy,” all fizzled at home. And audiences already rejected a movie involving King Arthur this summer, although that one didn’t have robots.

A $70-million opening for “The Last Knight” would mark a 30% drop from “Age of Extinction.” Taking into account the fact that “The Last Knight” is getting a five-day debut, it would also mark the lowest domestic bow in the history of the series. With a $217-million budget before marketing costs, the movie will have to do huge business overseas to be a success.

Looking to China

The question now is, how much does the domestic market really matter for the “Transformers” series? The last two “Transformers" movies grossed more than $1 billion worldwide and, for the most recent one, foreign ticket sales accounted for 78% of the total haul. China, where Paramount has benefited from elaborate marketing partnerships with local companies, accounted for $320 million.

“Transformers: The Last Knight” opens in most countries this week, including China, Britain and Russia. Chinese cinema giant Dalian Wanda Group has agreed to use its clout to promote “The Last Knight,” the company said during a high-profile Shanghai announcement ceremony this week. Marketing company Weying Technology is also backing the film’s promotional efforts in China.

There’s an asterisk on the Chinese box office, though. American studios reap 25% of the grosses from that country as part of a revenue-sharing agreement, which is less than the 40% to 50% share the studios take in from other countries.

ryan.faughnder@latimes.com

@rfaughnder