Definitely the highlight of Criterion's Monsters and Madmen set (although I have yet to see the fourth film, The Atomic Submarine, but I can't imagine I'll like it as much as this), and another undervalued Boris Karloff picture. Karloff in this one plays the (fictionalized) surgeon who discovers anesthesia. Unfortunately, he experiments on himself, and finds himself addicted to the concoction (which includes morphine and opium). This problem leads him into the manipulative hands of two murderous crooks (Francis De Wolff and a young Christopher Lee), who will steal the ingredients that he needs in exchange for the doctor's signature on the death certificates of their murder victims, whose corpses they are selling to medical researchers. Of course, this part of the film is inspired by the Burke and Hare murders, which was the subject of Boris Karloff's crowning achievement, The Body Snatcher. I would imagine that the makers of this film were very familiar with The Body Snatcher, and Corridors of Blood has that kind of literate air that Val Lewton injected into his pictures. It's not quite on the level of that film, or most of the other Lewton films, either, but it's a gem. And I needn't really say this anymore, but Karloff is outstanding. I almost feel sorry for the guy, getting stuck in the horror genre as he did. He was easily one of the finest actors who ever lived, but one who will always be ignored by mainstream critics.

Dr Thomas Bolton is determined in his quest to find a way to relieve the suffering of patients by somehow disconnecting the brain from the process and thus removing the experience of pain. His experiments have so far been failures and he has become somewhat of a joke between his peers. Self-experimenting with an opium-derived anaesthetic, Bolton gradually succumbs to addiction that only further feeds his drive for success in his studies. This addiction and destructive ambition leads him to the shadows of the criminal world and into the clutches of a den of those that would exploit him for all they can get.I recently watched a later film that featured Karloff and Lee (Curse of the Crimson Alter) and I assume that BBC2 must have been doing something of a mini season of such films because the following week they showed this film in the same slot. Corridors of Blood is a much better film than Crimson Alter due to much stronger material. The horror here is based on the descent of the main character into addiction and the world of Black Ben; a world of murder for small financial gains and a world that Bolton finds he needs for an increasing number of reasons. The addiction is the only "monster" of the film and to my pleasant surprise it is very well delivered by Karloff. I expected ham and what I got was actually quite restrained and engaging – his fall is built on good intentions and it is human and believable. The men he falls in with are also a convincing blend of man and monster as they murder and exploit for small rewards, they are sinister characters and they add another layer of darkness to Bolton's fall.De Wolff is good as the bear-sized boss of the group but of course most memorable is Christopher Lee, who is a gaunt figure all in black but gets most impact from the look of sheer dark menace that he manages not only to put on his face but also deep in his eyes. Day directs well and with his crew manages to build a good atmosphere while telling this human story. I'm not suggesting that it is a perfect film or incredibly insightful but it does well for what it is, providing an engaging character at the heart of the story. Well worth seeing for Karloff fans.

Dr. Thomas Bolton is one of London's top surgeons, brilliant and fast, he is however constantly troubled by the amount of pain his patients go through, for this be a time before anaesthesia. Painstakingly working on a formula to put patients to sleep during surgery, Bolton is convinced he has found a breakthrough, but upon trialling it in front of the board it goes terribly wrong. He continues undaunted, but as he keeps testing the formula out on himself he becomes badly addicted, unable to get the hospital board to sanction his research, he gets involved with a dastardly group of murderers who kill and then sell off corpse's to a suspect doctor.Make no (saw) bones about it, this is a wonderful Boris Karloff performance, the amount of sympathy and earthy fortitude he puts into Dr. Bolton is very impressive. The plot isn't up to much and fans of staple horror requirements will hardly get any titillation from it, but as a crime picture and a character study it comes out smiling and delivers the goods. The sets are very good, check out the frontal entry into the Seven Dials area, and now with better digital transfers the picture's black and white texture ripens the watching experience. It's a film that I suppose is easily forgotten quickly after the viewing, but it's well worth watching for Karloff's turn and an ending that is strangely sad but uplifting at the same time. 6/10

A surgeon, working on the very first anesthetic despite groanings from his medical colleagues and peers that the experiments would lead to certain failure, falls into drug addiction when he becomes drawn to the opium used as an ingredient within the formula. Under a drug-induced state, Dr. Bolton(Boris Karloff) is coerced into writing false death certificates signifying the loss of life from natural causes by Black Ben(Francis De Wolff) and his despicable female companion Rachel(Adrienne Corri) who thrive in the underbelly of London centered in a ugly little spot called Seven Dials..he does so, although Ben has his henchman Joe(Christoper Lee)suffocate paupers so that they can take the fresh bodies to anatomy doctors for wages. It's Burke and Haire repeated by this group all over again. When Bolton's first demonstration failed due to a patient rising from his seat and attacking the on-lookers watching the operation, due to not enough anesthesia being applied for complete unconsciousness, his medical faculty wish for his experiments to cease. Bolton's seduction with inhaling too much of the experimental anesthetic causes his surgery work to suffer, not to mention he loses sleep and scurries to the Seven Dials believing it's all an evil dream. Such as when his pocket-book, containing all his experimental notes, is lifted in Ben's grungy pub and the only way he can retrieve it is to sign a false death certificate, or when he goes to Ben in need of narcotics when the medical institution cuts him off..Bolton believes these unfortunate events are nasty members of a nightmare. The film shows Bolton's very life and career in turmoil as he makes a deal with the devil, so to speak, leading to a murder and theft as Ben & Joe plan to do away with the addicted doctor. What Ben and his cronies do not know is that Inspector Donovan(Nigel Green)is preparing to infiltrate his devious operation..but can the Inspector rescue Bolton from certain peril?Maybe the film is a bit dated in how drug addiction is portrayed(certainly one can see that in a more modern based picture, the ante would be raised and we'd see a much uglier side of addiction and grotesque behavior than presented in this film), but I thought Karloff does a fine job of showing a man with conviction, sorrowful and riddled with anguish at the sight of his patients suffering from such agony and pain through the horrors of surgery and amputation. Although his ideals and notions for creating a painless surgical method are challenged as fleeting and unrealistic, Karloff shows the dogged determination. Yet, Karloff also shows the downward spiral of a man swindled by those willing to take advantage of his addiction and one who can not acknowledge the very fact he is an addict. Good support from Betta St. John as Bolton's dedicated servant/friend Susan and Francis Matthews as his son Jonathan(the film has a budding romantic sub-plot between Susan and Jonathan). Christopher Lee, not surprisingly, is a revelation as the creepy, intense murderer Joe and De Wolff as the slimy Seven Dials boss always carrying a devilish grin, is also quite memorable. Pretty good little film, I must say. It seems the filmmakers put a lot of heart and thought into this..although, it doesn't hurt when you have Karloff anchoring your film and Lee stealing every scene he's in with that commanding presence.