The film has received almost universal critical acclaim and gained a Rotten Tomatoes rating of 95%.[5] The film received the Grand Jury's Knight Documentary Competition at the 2012 Miami International Film Festival,[6] and was nominated for the Grand Jury's World Cinema - Documentary prize at the 2012 Sundance Film Festival.[7] Besides, it won the Filmmakers Award at the 2012 Hot Docs Canadian International Documentary Festival.[8] The film has been in official selection for several international film festivals, including: South by Southwest,[9] Edinburgh International Film Festival,[10] True/False Film Festival,[11] New Zealand International Film Festivals,[12] Sydney Film Festival,[13] Revelation Perth International Film Festival,[14] Seattle International Film Festival,[15] and San Sebastián International Film Festival.[16]
It was nominated for six British Independent Film Awards for Best Film, Best Director, Best Debut Director, Best Technical Achievement- Editing, Best Achievement in Production, and Best Documentary. It was also shortlisted for an Academy Award for Best Documentary.[17] It was nominated for 2 BAFTA's at the 66th British Academy Film Awards for Outstanding Debut by a British Writer, Director or Producer and Best Documentary, winning the first.
UK-based film magazine Total Film gave the film a five-star review (denoting 'outstanding'): "Creepier than Catfish and as cinematic as Man on Wire, this is an unnerving story immaculately told and a strong contender for doc of the year."[18]
Peter Bradshaw, film critic for The Guardian, awarded the film five stars, writing, "This film is as gripping as any white-knuckle thriller: it is one of the year's best."[19]