Billy is unable to speak. She is a special effects make-up artist, working on a slasher movie shoot in Russia, where her sister Karen also works (Fay Ripley in her first main movie role) and her sister's boyfriend Andy, the movie's director. One evening she goes back into the building to collect something, but is accidentally locked in by the security guard. And when she goes to investigate a strange noise, she finds the studio being used for a snuff movie, and witnesses a brutal murder.
Mute Witness is a surprisingly tense thriller. When Billy is pursued by the two killers, she can't simply scream for help or call the police, and has to rely on her intelligence to survive. The studio setting - a decaying, grimy, cold, industrial type building - provides a unsettling and sinister atmosphere. And being surrounded by an unfamiliar culture and language adds to the feeling of isolation and helplessness.
In the central role, Marina Sudina gives a superb performance, having to convey so much through her facial expressions rather than her voice or dialogue. She brings Billy to life, as a likable and intelligent character, rather than a vulnerable victim. The other principle characters give decent performances (providing you aren't too distracted by Fay Ripley's 'American' accent). And Sir Alec Guinness makes a very brief appearance, though he does little more than sit in a car and speak a few lines of sinister dialogue. (Apparently his scenes were shot several years before the main filming of this movie commenced.)
My only criticism of the film is it seems to change direction in the final third. The first two-thirds is focused on Billy having to survive using her wits after witnessing the snuff movie murder. The final section shifts the focus onto a missing floppy disk, double-double-crossing cops, and a mafia-like organisation. The dark tone also changes, with Karen and Andy becoming bumbling comic relief characters. And more disappointingly, Billy's role becomes slightly more damsel-in-distress.
Despite saying all that, none of this spoils the film overall. The (extremely) tense first hour more than makes up for any shortcomings, and I'd say that part is a must-see for horror/thriller fans. Despite the very brutal murder at the start, this movie is more about the tension, the thrills and the atmosphere, rather than violence or gore. I'm surprised Mute Witness is not more well-known, and If you can find a copy, it's well worth giving it a look. 4.5/5