Producers: Naomi Watts, Peter Sobiloff, Mike Sobiloff. Trudie Styler, Celine Rattray and Jenny Halper   Director: Malgorzata Szumowska   Screenplay: Joshua Rollins   Cast: Naomi Watts, Billy Howle, Denis O’Hare and Parker Sawyers   Distributor: Bleecker Street

Grade: B-

Naomi Watts has already played a real-life character who’s confronted nature’s fury—in 2012, she was the wife in “The Impossible,” who along with her husband and son survived a tsunami that struck Thailand.  Now she takes on a New Hampshire blizzard and saves a stranded hiker in the process.  The fact-based “Infinite Storm” doesn’t have the scope of the earlier film, but it’s fairly effective as a tale of courage under extreme circumstances.

Watts play Pam Bales, a member of the White Mountains volunteer rescue team who undertook a solo climb toward Mount Washington, the tallest peak of the range, in the fall of 2010.  As an experienced hiker, she was well prepared, but as a storm came up she detected footprints in the snow and followed them to a young man in desperate straits.  She led John, as she called him, down the mountain through blinding snow and freezing temperatures despite his uncooperative attitude, and successfully got him to the station where both their cars were parked.  Rather than allowing her to drive him to safety, he jumped in his vehicle and sped away.

Only later did Pam learn the reason for John’s actions.  In a letter addressed to her squad, he explained that he had climbed the mountain to commit suicide, in despair that the girl he loved had died there.  His purpose now was simply to thank her and let others know of her heroic act.  The story later became the subject of news reports.

The film, shot in Slovenia under the direction of Polish helmer Malgorzata Szumowska, recounts the entire event from Bales’s departure on her climb through the descent, filled with hard choices and close shaves. (Joshua Rollins’ script is adapted from a description of the rescue by Ty Gagne.) The action is convincing not only because Watts and Billy Howle, who plays John, effectively portray the desperation of the characters’ plight—it must have been an arduous shoot for them both—but because the technical team ably captures the frigid, harrowing atmosphere of the locale.  For that one must also credit not only the spare production design by Katja Šoltes and moody blue-and-gray cinematography by Michal Englert, but the editing of Agata Cierniak and Jacostaw Kamínski, which keeps the running-time trim.  One should also note the effective but not overpowering score by Lorne Balfe, which together with Ben Baird’s sound design reflects the chilly surroundings, and the visual effects supervised by Szyman Kania.

There is a degree of mawkishness here, not only in the meeting between Pam and John added as a postscript, but in the flashbacks that are inserted to a traumatic experience in Bales’s own past.  Others will have to determine whether these are accurate reflections of the historical record or to what extent they’ve been added or embellished for dramatic effect.  Whatever the case, the dreamlike flashbacks in particular are dropped into the narrative in a way that’s obviously intended to create a sense of suspense that’s never really achieved.

But for the most part “Infinite Storm” is an effective dramatization of an act of courage under extreme pressure, showcasing another physically compelling performance by Watts.