Producers: Derrin Schlesinger, Piers Vellacott and Dimitri Doganis   Director: Michael Pearce   Screenplay: Joe Barton and Michael Pearce   Cast: Riz Ahmed, Lucian-River Chauhan, Aditya Geddada, Octavia Spencer, Rory Cochrane, Janina Gavankar, Misha Collins, Shane McRae, Antonio Jaramillo and Keith Szarabajka   Distributor: Amazon Studios

Grade: C

In “Encounter” director Michael Pearce and his writing partner Joe Barton attempt a cinematic conjuring trick that probably won’t fool most viewers and will have disappointed all of them, one way or another, by the time the sleight of hand is finally revealed.

Riz Ahmed, who rightfully won plaudits last year for his riveting performance in “Sound of Metal,” again brings his intensity to bear as Malik Khan, an ex-Marine who’s shown at the film’s beginning reacting to media reports of an infestation of earth by alien parasites that use insects to burrow into human hosts and take them over.  Using insect repellent and more primitive tools like fly swatters, he intends to save not only himself but his two young sons, Jay (Lucian River-Chauhan) and Bobby (Aditya Geddada).  They live with their mother Piya (Janina Gavankar) and her new husband Dylan (Misha Collins), who Malik believes may already have been infected.

So Malik sneaks into Piya’s house, rousts the sleeping boys from their beds and spirits them into his jeep for a drive to a base in Nevada where scientists are working on a cure to the problem.  He describes the trip to them as an adventure, a vacation on which they’ll be free to do much as they like so long as they’re careful to avoid interacting with strangers or calling attention to themselves.  When they do, he reacts with anger, though it quickly reverts to paternal concern marred by increasing nervousness.

The boys are initially happy to be with their father—Jay in particular looks on him as a hero, and has always been hostile to Dylan—but after an encounter with a policeman who stops them on the road they begin to have doubts which grow as the trip goes on and other observers intervene, including some who are positively dangerous.

By this time, however, our view of what’s happening has been radically altered.  The change is one of perspective: while the first half of the picture is told from Malik’s, so that we share his viewpoint no matter how skewered it might seem at times—we are, after all, familiar with the tropes of alien invasion from plenty of other movies, and thus prepared to accept their implausibility—Pearce and Barton now shift to those interpreting his actions in any entirely different way.  Octavia Spencer is introduced as Malik’s parole officer Hattie, and we learn of time he spent in prison as a result of a breakdown he suffered while in the service.  And Rory Cochrane shows up as FBI investigator Shepard West, charged with dealing with what’s happening as a case of child abduction.  Are the boys and Malik targets of parasite-controlled hosts attempting to thwart Malik’s fatherly mission, or is the entire tale he’s told his sons a delusion induced by PTSD?

One can imagine a treatment that could have continued juggling the possibilities for a considerable time, but “Encounter” doesn’t go that route.  It makes clear which of the two divergent viewpoints is the right one pretty quickly—indeed, one will have anticipated the shift fairly far in advance—and while Pearce tries to sustain suspense by escalating the danger of injury to the children by various means, none is terribly effective.  One episode, involving some vigilantes, is especially misjudged.

One can nonetheless appreciate the commitment of Ahmid’s performance, which never flags—indeed, is sometimes taken to excess—and the naturalness of the two boys in conveying the siblings’ growing apprehension over what’s happening to them and concern about their father’s stability.  Spencer and Cochrane, on the other hand, are so laid back that the sequences in which they take center stage are largely a drag.  Perhaps that’s intended to prove their professionalism under pressure, but it tends to have an overall deflating effect.

The technical crew—production designer Tim Grimes and cinematographer Benjamin Kracun—give the visuals a raw, gritty texture, and editor Maya Maffioli handles the shifting perspectives reasonably well, along with providing some creepy montages of the alien infestation early on, while Jed Kurzel’s score adds some grumbling notes of foreboding.

By the close, however, you’re likely to conclude that this is an “Encounter” better avoided.