Andrew Wyatt’s review published on Letterboxd :
Two scientists (William Jackson Harper and Rebecca Henderson) are assigned by their corporate employer to investigate a series of enigmatic wilderness sites where both cult activity and weirder phenomena are known to have occurred. Director Philip Gelatt draws from a host of cinematic influences – chiefly 1970s genre works like Silent Running (1972), Phase IV (1974), and Stalker (1979) – while still maintaining a sense of eerie novelty. They Remain has atmosphere in spades, and the film’s impressionistic images and unconventional editing underline the hallucinatory time slippage that the characters begin to experience. Unfortunately, there’s remarkably little plot to go along with all the mood. The film is more of a narcotic haze than a story, lacking any sense of rising action – just repetitive scenes of Harper wandering the woods and passive-aggressively sparring with his partner. Gelatt’s infatuation with elliptical mystery leads to narrative obfuscation, and he fails to resolve the dissonance between the film’s gaudier elements and its chilly sci-fi horror vibe.