Coming hot on the heels of the sleazy HOUSE OF WHIPCORD and the outrageously gruesome FRIGHTMARE, veteran exploitationer Pete Walker and his puckish screenwriter David McGillivray decided to stir up some more mischief, this time aiming their vitriol at the hypocrisy of the Catholic church, with a blackmailing killer priest who uses the tools of his trade (incense burners, rosary beads and communion wafers) to deal out death to non-believers. Given the hoo-hah the Monty Python team caused with LIFE OF BRIAN four years later, you'd have expected the controversy to rage as Pete and David had hoped it would, but HOUSE OF MORTAL SIN barely raised a murmur - most likely because it's a rather dull and restrained affair compared to their earlier exercises in wonderfully hideous terror. Anthony Sharp is fine in the lead as the crazy cleric, alternating between pompous bumbling and trembling mania at the drop of a hat, whilst Susan Penhaligon makes a memorably vulnerable victim, but the film feels too much of a cut-and-paste catalogue of borrowed elements (the mother fixation from PSYCHO, Sheila Keith basically reprising her WHIPCORD role as Sharp's demented housekeeper, the dysfunctional family business from FRIGHTMARE) to really ring true. The set-piece murders are impressive, and the ending is as bleak and as desolate as you'd expect, but the film contains more padding than a cheap mattress and Walker seems to have confused tension with tedium in several scenes. Still, it's entertaining enough for a slow evening.