“Schizophrenia... a mental disorder, sometimes known as multiple or split personality, characterised by loss of touch with the environment and alternation between violent and contrasting behaviour patterns.”

An upset chap in a red bobble hat who carries what can only be described as a knife (as opposed to not being one, he said in a tortured reference to Crocodile Dundee… it’s a big knife that’s what I’m trying to get across) is deeply unhappy at the prospective marriage of a famous ice skater to a bloke who runs a carpet factory.

Sam, the ice skater (Lynn Frederick) has a friend who's a psychiatrist and another who isn’t, but is Stephanie Beacham. On Sam’s wedding day red-bobble-hat-man (who's been having very bloody flashbacks about a naked woman being stabbed to death) manages to infiltrate the ceremony and deposit his bloody machete next to the cake - Sam conveniently picking it up when asked to "cut the cake". That's enough to put a dampener on any party. Once home, she answers the phone to "Jean? Is that you, Jean? Did you like my present?" yet shrugs it off (like you would) as "some nutcase" who's "phoned twice already". What's more, before the happy couple go to bed ("I thought you'd never ask"), hubbie notices that everything's been moved around - and Sam gets scared by a big joke-shop spider and bat combination in the bed.

It's not long before we're treated to a typically 1970s exploitative “homage” to Psycho (yes, another one) as Sam, having a quick shower, gets terrorised by a knife wielding hand. Not as scared by this as she probably should be, she then chooses to explore the house wrapped in what appears to be the tiniest flannel she can find before being jumped on by her housekeeper, who warns of seeing evil spirits. We’re not that far into the film, and it appears everyone's got a screw loose. As, apparently, has Sam - she's shopping in the local supermarket (baked beans 13p, New Zealand butter 19p) when she starts hearing someone calling her name and steals a butcher's cleaver.

Sam is by now getting worried, and it doesn't help when she gets home and finds a picture of her dead mother in the house. She goes to Leonard (her psychiatrist friend) and confides that she actually does know the man who's been following her - his name is William Haskins, he was her mother's lover and "he wants to kill me". What's more, he killed her mum (apparently) and we're treated to the event in all its gory, naked detail with Sam intoning: "I was seven... seven... seven... seven... Blood... pieces of flesh... he was ripping her to pieces..."

Of course it's not long before Leonard is murdered himself (throat cut in his groovy brown Mk1 Granada), but no-one seems particularly bothered by this, particularly Sam, who tells the police matter-of-factly: "Yes, I knew him... I must have been the last person to see him alive."

The police, in their usual British Horror Movie style, don't arrest Sam for this, or even give her any protection against Haskins, but just leave her on her own again - cue Haskins gurning at the window and another bloody knife turning up in the flat. To get over this, Sam decides to go to a seance with her housekeeper's daughter where the medium's eyes go white and she utters (in a man's voice) "My killer's here!"

Sam lends her groovy yellow coat to the housekeeper's daughter, who immediately gets bludgeoned in the face with a hammer and pushed under the wheels of a bus. And it's not long before the housekeeper (turning up for work despite just finding out her daughter's been murdered) gets a knitting needle in the head for her devotion to duty.

Things are moving nicely (and stupidly) towards the excellent climax in the carpet factory, where it transpires that the assorted bloody knives are some kind of DIY psychology on Haskins' part, and the immortal line "You're not well... you're two different people and one doesn't know about the other!" is uttered.

Schizo may be stupid, but it's classic 70s exploitation fare. So what if it's a whodunnit where you already know whodunnit? It's also a comedy classic - the hackneyed scene at the end when one character, already in a bit of a state, staggers pleading towards another who's just standing there going "phew" a lot, is absolutely hilarious.