David Mackenzie’s Relay is a rare kind of modern thriller: coolly intelligent, quietly unnerving, and built on ideas rather than explosions. It unfolds in a version of New York that feels both contemporary and haunted by the ghosts of older conspiracy films. At the center of it all is Riz Ahmed, giving one of his most quietly magnetic performances as Ash, a professional go-between who makes a living brokering deals between whistle-blowers and the corporations they threaten to expose. It’s an ethically ambiguous job, and the film never lets him or the audience forget it. The concept is simple but ingenious. Ash uses an old assistive communication system, a phone relay service originally designed for people who are deaf or hard of hearing, as his cover. It allows him to pass information between opposing parties while concealing his own identity. He is a middleman of secrets, a man who thrives in the murky space between truth and silence. When Sarah Grant, played by Lily James, contacts h...