“A dual personality that without the knife is incomplete!”

Toothless crones shake their fists at the camera as a man is taken, protesting, towards the gallows. From an upstairs window, a busty strumpet looks on and chews her apple suggestively. One quick quiver of the condemned man's suspended legs and it's all over. His body is taken away and dumped in a coffin full of quicklime. Someone, for some reason, inserts a knife into the wooden box before it is shut - and then the doctor present at the funeral faints dead away. The credits roll.

It's immediately apparent from this little vignette that this is going to be some kind of weirdy 1950s mystery film. The viewer is left without the slightest idea of what is going on.

Anyway, enter Boris Karloff, no less. It's 20 years later, and he is James Rankin, a novelist obsessed with the hanged man - who turns out to be a convicted killer named Edward Styles - or to give him his correct monicker, "The Haymarket Strangler". In fact, you could even say that through his obsession, Karloff is in the "Grip Of The Strangler" (and you think they just threw these films together).

"There was nothing in Styles' life to say he was capable of such violence," proclaims kindly Rankin, who is trying to prove the dead man's innocence. He thinks it's far more likely that the murderer was Dr Tennant, the man who collapsed at the funeral and who also (dun dun dunnn!) performed the autopsies on the Strangler's five victims.

Karloff (the absolute master of eyebrow acting) later discovers that, to add to the evidence, Dr Tennant later went mental and ran off with a nurse. In fact, it's amazing the amount of information Rankin is getting in a very short time. Surely there's more to the film than this? Oh, there is, there is...

The evidence against Tennant mounts up thick and fast - the knife is missing from his old doctor's case, and he also kept a notebook detailing the killing of the women. Rankin, by now obviously very close to the identity of the real killer (well duh) says his reasons are purely humanitarian - he wants a change in the legal system to stop this ever happening again.

He pays a visit to the can-can club which appears to be the central point for all the murders, called The Judas Hole, and is told that Dr Tennant was always there, pestering the girls. He also discovers that Tennant's father beat him, and his mother didn't care. Rankin has a theory; "You mean he killed while he was in some sort of a trance?"

Rankin, along with his assistant "McCall" (who is in love with Rankin’s daughter) is by now obsessed with finding the knife, for some reason - despite having discovered who the actual murderer was. Why does he need to find the knife? If you haven't fallen asleep or wandered off to do a jigsaw or something, you're about to find out...

Rankin makes his way to Styles' grave in the dead of night, and after having several pigeons chucked at him by off-screen SFX men, starts digging in such a fantastic way it's a shame someone didn't patent it as "The Karloff Method". Not particularly effective, but looks great.

Spoiler alert, here comes the "twist": Boris finds the knife amongst the bones of poor old Styles (which, incidentally, he has a flagrant disregard for, for a man who in the last scene fainted dead away at the sight of someone being flogged). On touching it his hand withers and his face contorts into that of a hideous monster. Let's hope for his sake the wind doesn't change. It's just like the transformation scene in An American Werewolf In London. Except it isn't. Although considering it's all in the method, dear, it is quite impressive.

A transformed Rankin makes his way to The Judas Hole and slices up young Pearl, a dancer (who wears pearls). He makes his escape straight through the busy club (as all good murderers do) but when Rankin wakes up, normal again, he remembers nothing.

"I'm committed," he says (he should be, obviously): "I can't turn back now."

On visiting the club the next day, comically no-one recognises him (sans gurn). As the club owner, Cora, tells him: "This is your doing, Mr Rankin..." (you're not kidding) "It was the same man... the very same man... I'd say that if I was face to face with him!" You are! Are you blind woman? It's obviously Rankin! Rankin is Tennant! And it's only taken 49 minutes to get to this. Finally, the plot gets going. "Leave me alone.." says Rankin. "I'm mad..."

He kills his wife, and the film (and its transformation sequences) lurches into Dr Jekyll territory (except without the potions). Rankin now tries to confess, but no-one will believe him. Instead they lock him up for being mad. But he's complaining they won't believe he's a murderer. Bizarre...

He uses the gas lamp(?) in his padded cell to set fire to the cell and then stabs a guard to death with a shard of glass before making his escape.

This leads to a comical exchange between a frantic guard and a kitchen floozy: "Have you seen 'im... the scaped lunatic!"

"Course oi 'ave... 'e's under these spuds!"

All of a sudden, everyone believes Rankin, and the film races towards its inevitable tragic conclusion.

"A dual personality that without the knife is incomplete." Exactly. Grip Of The Strangler is bizarre, quite likeable, a bit slow, and strange.