There's still one kind of dread genre filmmakers reliably stir up: that fear that everything we've been watching is going to be upended by some last-minute twist so big that nothing preceding it actually needs to add up. After its first-rate opening, in which a pair of MIT code-bros pick through a creepy desert house in the middle of the night, The Signal never stops suggesting it's barreling toward one of those twists. There are clues everywhere. The chief code-bro wakes up in some hospital where the clocks don't work, the tech's all Lost–island retro, and a doctor played by Laurence Fishburne in a hazmat suit is asking him to identify simple shapes and colors.
"Have you had an encounter with an E.B.E.?" Fishburne asks. He pauses, allows some drama to swell, and clarifies: "An extraterrestrial biological entity?"
Fishhburne's character records that conversation on a '70s cassette player. This is not how non-twist doctors behave.
All code-bro, played with panicky incomprehension by Brenton Thwaites, knows is that he's locked in a bedroom, that he might be infected with extra-terrestrial contagions, and that his MIT buddy -- imprisoned elsewhere in Twist-Ending Hospital -- occasionally whispers to him through an air vent. Since no one could believe that's not set up by Fishburne et al., the audience is stuck waiting these scenes out to see what's really going on. When it's revealed, the surprise makes most of what came before not just inconsequential but risible. Here's the question worth shouting afterward: If it was actually [INSERT SPOILER HERE] all along, why would [SPOILER] ever have bothered to [ALMOST EVERYTHING THAT HAPPENS IN THE MOVIE]?