“Stephen, Stephen, there is another man, my darling!”

Alan (Maurice Kaufmann) and his American fiancée Patricia (Stefanie Beacham) have arrived back in the UK, and before you can say “know your place woman, this is the 1960s for goodness’ sake”, she’s announced she really must go and apologise to her previous boyfriend’s mother, ignored Alan’s almost-reasonable suggestions that this doesn’t seem like a great idea, and “borrowed” his car, figuring she’ll sort the whole “wrong side of the road / manual gearbox” issues later in the journey.

Said ex-boyfriend is dead, and his grieving mother, Mrs Trefoile (Tallulah Bankhead) lives in a run-down gothic mansion on the edge of a picturesque English village. Patricia roars in without a care in the world, seemingly oblivious to the horror/thriller caricatures with whom Mrs Trefoile has surrounded herself. There’s the taciturn wild-eyed and gun-obsessed handyman (Peter Vaughan), his wife, the grim and no-nonsense housekeeper (Yootha Joyce) and the simple-minded garden boy (Donald Sutherland, yes that one).

Patricia is welcomed by Mrs Trefoile with open arms and an immediate hope that her son Stephen “died a virgin”. The American remains sanguine as Mrs Trefoile (who is clearly a loon) ramps mild indignity after mild indignity on her – dictating what clothes she should wear, wiping makeup from her face, feeding her vegetarian food (hey it was the 1960s, this kind of thing just was not done in polite society) and subjecting her to endless fire and brimstone sermons. Patricia notices that all the mirrors in the house are removed (but not, of course, their frames), yet keeps on smiling and reminding herself she’s only there for a day.

Finally, the penny drops that all this might be a tad more than just British eccentricity after a visit to the local church, when Mrs Trefoile announces that she considers Patricia to still be married to her dead son. Even though they never actually married, and, as I just mentioned, he’s dead.

“You never intended to stay true to Stephen, so I must keep you!” announces the old fruitcake, locking Patricia in her bedroom.

Realising they’re “all insane, ALL of them!”, Patricia makes her first escape attempt by throwing a chair through the window, and Mrs Trefoile retaliates by pulling a gun on her. Which rather pisses on her chips.

Things then escalate quickly. A tussle sees Patricia accidentally stabbed with a pair of scissors, her clothes are all destroyed at Mrs Trefoile’s insistence, and after a failed attempt to bribe her way out, Patricia ends up crashing through a glass roof and almost drowns in the nearby river.

Meanwhile, Mrs Trefoile is keeping her dead son informed of all the goings-on: “Stephen, Stephen, there is another man, my darling!”

From then on it’s a race against time as Alan turns up in the village looking for his missing fiancée, and poor Patricia suffers further indignities as her merry band of psychotic kidnappers begin to turn on themselves. Even switching on her considerable allure doesn’t work. Well, not in the way she’d hoped anyway.

Fanatic is an absolute hoot from beginning to disco-lit end, with everyone (especially a reputedly constantly drunk Bankhead) giving it the full beans. It’s a gothic delight, and you might even be able to trace its influence into the early 70s as it has a similar look and feel to cluttered-house-full-of-murderous-characters offerings like Texas Chainsaw Massacre (although I’ll admit I may be pushing it a bit there).