I'll leave it up to others to debate whether 'Mania' (a.k.a. 'The Flesh and the Fiends') is technically a horror movie. While dealing with horrific events, and told in a fashion with plenty of creepy moments, I would still say it isn't horror myself. Whatever you classify it as it is a seriously underrated thriller with strong performances from an above average cast. Director John Gilling went on to make the Hammer classic 'The Plague Of Zombies' later in the 1960s, and stars Peter Cushing ('Twins Of Evil') and Donald Pleasence ('Halloween') both made a strong impact on the horror genre, so fans will be interested to see this for those reasons alone. Cushing is excellent as the stubborn and driven Dr. Knox who needs a steady supply of corpses to dissect, and Pleasence plays the slimy William Hare, who along with his equally creepy colleague William Burke (George Rose), gleefully fills that need. The only problem is that Burke and Hare have no qualms about where the corpses come from, or whether they need a little "help" along the way. Burke and Hare were real body snatchers, but I have no idea just how historically accurate the events depicted in this movie are. But it certainly is entertaining and worth watching for the terrific performances by Cushing, Pleasence and Rose, and also for Billie Whitelaw ('The Omen') who has a small but important supporting role as the love interest for one of Dr. Knox's medical students (John Cairney - 'Jason And The Argonauts').