In his home office by the Thames, Dr Leo Whitset (Peter Copley) has been found by this housekeeper dying on the floor under his desk, a gunshot wound in his temple and the weapon lying next to him. With his final breath he insists he killed himself, and the police are content to accept that explanation, after all he did not have an enemy in the world, and his patients all thought very highly of him. One of those patients was television journalist Alex Stedman (Stephen Boyd) who delights the British viewing public with scathing views on his fellow Americans, but he is having a hard time processing what has happened to his psychiatrist. That feeling will be exacerbated soon...
This is when Whitset's fourteen-year-old daughter Catherine enters the picture, played by that precocious talent of the nineteen-sixties Pamela Franklin at the height of her promise, a promise that sadly went unfulfilled when she took on grown-up roles in the following decade. Still, you could watch her in material like this and lament what might have been, because she acted everyone else off the screen, though it was a close-run thing with her co-star Boyd who was obviously very enamoured of producer Robert L. Joseph's screenplay. Joseph was a playwright who dabbled in film and (mostly) television, and with this he clearly had ambitions on the level of Citizen Kane.
That was, at least according to the structure and some of the dialogue that was reminiscent of Orson Welles' much-revered classic: they both took the form of an investigation into a much-respected dead man, though with this the investigator had a far more active role, having been personally affected by both his life and his death. Stedman gets involved in what the police did not when Catherine implores him to look into the passing, since she does not believe her father was a suicide, nope, she believes he was murdered, and she has a very good reason for that belief, but the fact remained Stedman then had to visit three patients in turn and work out which was the killer.
That was the theory, anyway, though this was one of those mysteries where you were meant to be asking yourself, hey, what if the protagonist is the killer and isn't aware of it? He is in psychiatric treatment, let's not forget. But Joseph's conception of mental illness was not one that would chime with reality, certainly here it is a source of shame for the afflicted, which can easily be the case, but the idea that kind of fragility can hide a murderous intent belonged back in the days of old dark house thrillers with mad relatives locked away in the attic, nothing like as savvy as the film seemed to think it was being, and must have looked dated for a supposedly serious film even back when this was released. Therefore, no matter how well-acted it was, The Third Secret looked a little silly under closer examination.
The manner in which it hid this was with lots and lots of talk, which lent the proceedings a static air, especially when the dialogue was as self-regarding as it was here. While Boyd got to flex his thespian muscles against suspects Richard Attenborough (art dealer who desperately wants to be an artist), Diane Cilento (secretary who has trouble with relationships) and Jack Hawkins (judge who pleads his mentally unstable past be kept hidden), the heart of the picture were the scenes between Boyd and Franklin. Many took place on a bank of the Thames outside the Whitset family home Catherine is reluctant to leave behind, despite her aunt and uncle supposed to be taking care of her, and their chats hinted at something unhealthy between the teen and the older man that neither can fully face up to or admit to. When her uncle flies into a rage and basically accuses Stedman of grooming the girl, it may be what you were thinking too, but Boyd managed to convince us that was not consciously crossing his mind. Nevertheless, this slightly creepy element lent the film an uncomfortably compelling air its absurdities didn't quite mask. Music by Richard Arnell.