I was unfamiliar with this seemingly overlooked mid-sixties gem until very recently, when it aired on late night TV, and after watching it a few nights back, I now consider this a frankly criminal oversight. Whilst not a horror film in the traditional sense, it arguably skirts the edges of the genre, as great thrillers often do; obvious examples that spring immediately to mind include a lot of film noir, some Hitchcock classics and the gialli of Bava, Argento, Fulci and others.
It was only a matter of time before someone decided to pit the world's greatest detective (well, tied with Batman at least) against, quite possibly, the most infamous villain in the annals of criminal history, Jack the Ripper. Indeed, there was apparently a Spanish language Holmes pastiche entitled Jack el Destripador that appeared not long after the murders. This literary flight of fancy would obviously not be a singular occurrence; on the contrary, it has inspired many writers, filmmakers, and even video game makers over the years.
This particular filmic incarnation of the idea is especially intriguing in that it suggests elements (albeit as fictional grist for the mill, as opposed to serious speculation regarding the real murders themselves) of the Royal Masonic conspiracy, later theorised by Stephen Knight in his highly controversial (and now largely discredited) 1976 book, Jack the Ripper: The Final Solution, which itself would later form the basis for what is arguably Alan Moore's magnum opus, From Hell (original series 1991-1996; collected edition - 1999). Also, it would be used again in a later film, Murder by Decree (1976), directed by Bob Clark (director of the seminal, pre-Halloween slasher, Black Christmas) and featuring Christopher Plummer as Holmes and James Mason as Watson.
A Study in Terror stars John Neville (probably best known for playing the title role in Terry Gilliam's The Adventures of Baron Munchausen) as the superlative sleuth and Donald Houston (Clash of the Titans) as his ever faithful friend. Robert Morley (the guy with the poodles from the brilliant Vincent Price vehicle Theatre of Blood) is delightful as Sherlock's long suffering brother Mycroft, although he is sadly somewhat underused. Also, keep an eye out for appearances from the young Barbara Windsor and Judi Dench.
I won't attempt to provide a detailed synopsis of the film as it's sufficient to know the initial setup, already detailed above. As far as I can tell based off my first viewing, the plot seems to be scrupulously constructed (i.e. watertight and lacking holes), and the various deductions Holmes makes are brilliantly elucidated by the writers, Derek and Donald Ford. In fact, whilst I would say that all involved (both cast and crew) collectively and consistently deliver the goods throughout, it was the quality of the writing that stood out for me as the film's greatest asset.
What also makes the movie highly enjoyable is its rich mix of horror, intellect, action, pathos and humour. Some of the murder set-pieces are cleverly staged, using simple elements like water and red-lighting to quite startling effect. At one point, our dynamic duo get to engage in a bit of the old fisticuffs in a back alley scuffle with some hooligans; amazingly, Sherlock manages to keep his top hat on throughout the entire thing. And there are moments that frankly made me laugh out loud, such as when Holmes and Watson go to the pub, dressed to the nines. The landlord, spotting that they're obviously loaded, doesn't think twice about pushing a semi-conscious patron off his chair to make room for these apparent high rollers.
Finally, the production design, as is to be expected with a film of this vintage, is the studio-bound, dry-ice gothic familiar to many Hammer productions; needless to say, it conjures both the ideal atmosphere for a cinematic interpretation of a Ripper story and some appropriately autumnal ambience for an October evening's viewing. Holmes fans unfamiliar with this title should seek it out immediately.