Review: 'Relay' is an entertaining throwback to '70s paranoid thrillers, one that presents Riz Ahmed as an Everyman action hero for the 21st century.

The golden era of paranoid thrillers was the 1970s, in the days of “Three Days of the Condor” and “The Parallax View,” and director David Mackenzie’s “Relay” shows why modern technology it’s harder to make those kind of movies — and finds an ingenious old-school of getting around that problem.

The action starts with guy named Hoffman (Michael Maher) meeting a CEO (Victor Garber) in a New York diner — a meeting to arrange the return of documents that prove the CEO’s pharmaceutical company was hiding data that showed their new wonder drug was actually killing people. Hoffman had stolen the documents, but got cold feet when the company harassed and threatened him.

All of this is prologue, and the character Mackenzie is concerned with is near the diner, watching the exchange from a distance. This character, played by Riz Ahmed and not identified by name until late in the movie, is a fixer who plays a low-key form of blackmail — arranging for such documents to go back to their secretive sources, but hanging onto a copy as insurance to keep the companies from threatening their former employees.

Once Ahmed’s character and his methods are introduced, Mackenzie and rookie screenwriter Justin Piasecki introduce someone new. She’s Sarah Grant (Lily James), a biotech scientist who has paperwork showing that her company’s new GMO wheat hybrid has some deadly side effects. Sarah reports she’s been harassed and threatened, and she’s heard about somebody who can make problems like this go away.

The method of contact between Sarah and Ahmed’s character is the clever wrinkle in Piasecki’s script, and a technological throwback to the “Three Days of the Condor” era. It’s an old-school TTY teletype, a device used by deaf people to use the telephone. Ahmed’s character uses the teletype in connection with a relay service in Yonkers, where operators read messages to and from deaf people. What makes it foolproof is that, because of the provisions of the Americans With Disabilities Act, such relay services never record calls or save the information exchanged in them — a cool way to get around modern surveillance techniques.

Not that a security crew that’s been harassing Sarah isn’t willing to try. They are led by Sam Worthington (“Avatar”) and Willa Fitzgerald, and their cat-and-mouse sequences with Ahmed are so electric they make typing a tension-packed experience.

Mackenzie (who directed the riveting neo-Western “Hell or High Water”) puts the action on the Manhattan streets, making it the second movie in as many weeks — after Spike Lee’s “Highest 2 Lowest” — to deploy the geography and atmosphere of the Big Apple so cleverly. 

The ride is so engaging that you think it can’t last. And, unfortunately, it can’t. The story runs out of gas toward the end, to the point where an observant filmmaker can spot Piasecki’s big twist about 20 minutes before it arrives.

Even when that happens, the pleasures of watching Riz Ahmed think his way through this intense scenario is still enjoyable. As his character applies his brains and an ability to blend into the New York scenery, Ahmed shows he’s a perfect choice for a 21st-century action figure — someone who stands out by blending in.

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‘Relay’

★★★

Opens Friday, August 22, in theaters everywhere. Rated R for language. Running time: 112 minutes.