On a dark and stormy night a sinister figure in black strangles Lady Morley (Mary Nell Santacroce) in the back of her limousine then bludgeons Lord Morley (Fred Stuthman) out cold before sending the car into a lake. Scotland Yard's two most dim-witted detectives Inspector Winship (Don Knotts) and Dr. Tart (Tim Conway) arrive at Morley manor a few days after receiving a letter urging them to investigate. That the letter was seemingly sent by Lord Morley himself some time after he died is but one of many mysteries soon perplexing the slapdash sleuths. After accidentally exploding a local gas station (don't ask), Inspector Winship and Dr. Tart meet beautiful heiress Phyllis Morley (Trisha Noble) whom they come to believe is in danger from the mysterious black-clad phantom skulking the grounds. Suspects include menacing manservant Justin (Bernard Fox) for whom mere mention of the word 'murder' provokes a violent rage only cured by a swift knee to the groin from the no-less malevolent Nanny (Grace Zabriskie). An array of oddballs turn up dead around the manor as Inspector Winship and Dr. Tart bumble from one mishap to another trying to find out what is going on.
After a successful run of family comedies for the Walt Disney studio Don Knotts and Tim Conway wound up in this farcical fright-fest co-produced by TriStar Pictures and Roger Corman's New World. Co-written by Conway himself The Private Eyes not only turned out to be the veteran duo's finest comic vehicle but also, supposedly, the most profitable film Corman ever made! It is an affectionate spoof of old-fashioned murder mysteries and all the thundercrack clichés of haunted house movies. Jacques Haitkin's shadowy cinematography gets the spooky mood spot-on and the film boasts lavish production values with North Carolina a surprisingly convincing stand-in for the English countryside. Except for the two leads everyone adopts a cod-British accent that, along with the mock English setting, adds a surreal air. Admittedly this style of spoofery owes a debt to Mel Brooks although The Private Eyes shuns vulgarity for a family friendly tone that harks back to Tim Conway's movie spoofs on The Carol Burnett Show.
It is the sort of comedy where the limping butler says "walk this way" whereupon Winship and Tart mimic his shambling movements. Some may find their broad, family friendly humour kind of corny but the fact remains the gags are frequently funny and endeared the lovable Knotts and Conway to a generation of children. In his first film as director, Lang Elliott, founder of TriStar Pictures, deftly mixes goofy laughs with genuine suspense (notably the torture chamber scene and a tense sequence inside a trash compactor straight out of Star Wars) that make the jokes that much funnier. Elliott was more active as a producer, including another self-scripted comic vehicle from Tim Conway They Went That-A-Way & That A-Way (1978), than director. He re-teamed with Conway for one of the comedian's many straight-to-video vehicles for his Dorf character, Dorf and the First Games on Mount Olympus (1988) but also directed Cage (1989) where Lou Ferrigno portrayed a mentally-handicapped action hero. It was not a comedy.
There is a cosy familiarity about Knotts and Conway's bumbling duo, taking a cue from Stan Laurel and Oliver Hardy, along with the horror comedies of Bob Hope, especially The Ghost Breakers (1940) and The Cat and the Canary (1939). Conway plays the dumb guy with a knack for useless inventions (including a 'Time Gun' that fires only once every hour!) while Knotts, in Sherlock Holmes deerstalker and cape, is the increasingly exasperated one wrongly convinced he is smart but actually just as dumb. While the supporting players, including future Twin Peaks stalwart Grace Zabriskie and Australian pop singer and actress Tricia Noble, who went on to play Natalie Portman's mom in Star Wars Episode III: Revenge of the Sith (2005), acquit themselves admirably The Private Eyes is really Knotts and Conway's show. Their exuberant slapstick schtick proves wholly engaging from the running gag involving carrier pigeons to Tart's befuddled reaction to the poetry-loving murderer's inability to rhyme.