Riz Ahmed has bugs on the brain in the disappointing genre mishmash Encounter

In the opening minutes of Encounter, a mosquito-like creature pierces its proboscis through a protective layer of human skin, going deep into flesh and blood. The little bug the attacker deposits inside its victim scuttles along vessels, burrows through connective tissue, and then explodes, jettisoning particles of itself outward to spread throughout the human body. The creepy-crawly tension of that early sequence teases the effective body horror filmmaker Michael Pearce weaves throughout Encounter. But the image also serves as a handy metaphor for the film’s failings: the way it infects an intriguing thriller of trauma and paranoia with invasive, consuming melodrama.

Co-written by Pearce and Joe Barton (who’s attached to an upcoming Cloverfield sequel), Encounter begins with that unsettlingly timely depiction of disease transfer. This is the greatest fear and motivator of former soldier Malik Khan (Ahmed). He sees bugs everywhere—flying out of motel-room walls, materializing inside people’s eyes—and his training from 10 tours served as part of the Marine Raider Regiment informs his response to this enemy that he can’t convince anyone has invaded Earth.

Malik moves at night. He keeps his head down. And he tries to save the people he loves: his sons, 10-year-old Jay (Lucian-River Chauhan) and 8-year-old Bobby (Aditya Geddada), who live with their mother, Piya (Janina Gavankar), Malik’s estranged wife. Is he protecting his children by coaxing them out of their beds in the middle of the night, ushering them into his car, and then driving away with them from Oregon to Nevada? Or is that just kidnapping? Encounter plays coy for a while with the distinction between paternal protectiveness and crime, aided by unsettling imagery.

Casting a man of South Asian heritage as a former star Marine is, on its lonesome, a pointed choice, given the kind of actors usually enlisted to portray American military heroes. Ahmed’s customary blend of braggadocio and vulnerability works to his favor here, whether he’s pithily dismissing one character’s racist suspicions about his allegiance or insisting to his sons that he’s their “cool-ass dad.” He has good chemistry with Chauhan and Geddada, and his physical grace comes in handy during the film’s demanding action scenes, as he throws his body into a scrappy fistfight or moves lithely through a massive shootout. Encounter relies on Ahmed’s pirouetting between mania and despair, loneliness and love, to secure our confidence in Malik’s certainty… while leaving just enough room for doubt.

Throughout, Pearce draws many elements from the the genre playbook. There are villainous bugs like the ones that prowl Men In Black and Starship Troopers. There is a lone man who no one believes, à la Independence Day and 12 Monkeys. And the anxiety of lost time and opportunity recalls Inception and Jacob’s Ladder. This many tropes require a particularly unique narrative to bind them together in an unexpected way. Yet as the film reveals its intentions around Ahmed’s character, too many scenes rely on superficial dialogue and contrived situations to push the plot along.

Pearce builds tension so effectively in the film’s first half with extreme closeup shots of insects, skittering sound effects, and Ahmed’s frenzied energy that the filmmaker’s eventual abandonment of those elements for a more straightforward drama feels like a missed opportunity. For all the fantastical stuff, including some unnerving flourishes (fast-moving bugs, mutated faces), Encounter is more message movie than monster movie. And the further it strays from sci-fi and horror, the more its propulsive energy flags.

It doesn’t help that the supporting characters are so deeply underwritten. Like so many movie kids, Jay and Bobby are only as intelligent or as foolish as each scene requires. Their inconsistency hampers the film’s pacing, particularly in its second half—including a staggeringly silly choice that Pearce and Barton mistake for a movingly noble one, in a final act that feels lifted from a much more treacly movie. Meanwhile, Octavia Spencer is capable of much more than what’s required of her role as Malik’s worried parole officer, Hattie. What she’s mainly asked to do here is sustain squints and frowns as expressions of concern and deliver expository dialogue about criminal categorizations and psychological profiles. Encounter keeps the relationship between the two adult characters merely functional, despite Spencer’s self-assured work.

In the end, this is a film that hits its marks but fails to step into its own. The film’s spookiness is well-deployed, but not enough so that Encounter succeeds as horror. The script includes some revealing exchanges about post-traumatic stress disorder, while underemphasizing how the decades-long War On Terror corrupts those who fought it. Ahmed’s performance is intuitive and ferocious, but his cast-mates are stuck with characters so un-nuanced that they fail to stand apart. “Pretty out-there stuff,” someone says of Malik’s theories, but Encounter stumbles by not going far enough.