A remarkably creepy and subtle evocation of dread, from a typically nuanced Nigel Kneale script. What if ghosts are simply phenomena that have simply been poorly described? That's just what a team of computer specialists, on the trail of a new recording medium, attempt to do when they discover that the old mansion in which they are conducting their work is haunted by the ghost of a victorian maid. Unfortunately, they discover too late that a rational explanation does not mean an end to the terror... TV drama as it should be done sadly, we'll probably never see its ilk on British TV again. Still, at least those nice chaps at BFI have released it on DVD.