A man types a message. An operator reads it over the phone. The person on the other end answers, and the operator types the response back.

That doesn’t sound like much of a movie.

But Relay takes that exchange and makes it surprisingly tense. You start paying attention to the wording. The pauses. Who knows what, and whether someone has just said more than they should.

Suddenly, you’re leaning forward watching people communicate through a third party.

It works.

Riz Ahmed plays a fixer who arranges deals between corporations with secrets and people holding information that could hurt them. His job is to negotiate a way out—money changes hands, documents come back, and ideally everyone lives long enough to move on.

His own survival depends on keeping his identity hidden. One of his tools is a telephone relay service, designed to let people with hearing or speech disabilities communicate by phone. He uses it to keep his voice out of the conversation.

Then a woman played by Lily James needs his help, and an already delicate operation becomes considerably more dangerous.

That’s enough plot. The pleasure is watching him work.

There’s something satisfying about a movie that lets you follow a capable person through a complicated process. He has rules. He has precautions. He’s thought about things you haven’t thought about yet. You’re trying to understand the plan while wondering whether the people pursuing his client are catching on.

And Ahmed makes you believe he can do this.

He isn’t the prototypical Hollywood thriller lead—the imposing guy who enters a room and immediately looks like he can handle everyone in it. His character is watchful, reserved and someone you could plausibly pass on a crowded sidewalk without noticing.

For this particular movie, that’s a considerable advantage.

He needs to disappear into the city. You need to believe he survives by noticing trouble early and thinking his way around it. Ahmed gives him that credibility without having to announce how clever he is.

He pulls it off.

The relay service adds to the tension because nobody can rush it. Even an urgent message has to be typed, read aloud and answered. When someone’s safety depends on the next exchange, that wait starts to feel awfully long.

Apparently, I’m not alone in enjoying this one. Relay has 82% from critics and 89% from verified audiences on Rotten Tomatoes, along with a solid 7.0 out of 10 on IMDb.

If you’re in the mood for a clever thriller with a lead who keeps you interested without saying much, put Relay on your list.

You might be surprised how invested you get in the next phone call.