Here are the only two things I can attribute the entire existence of this movie to. First, Rock Hudson had been an iron-jawed Hollywood hunk in movies like Giant for so long he was bored with it and – perhaps struggling to reconcile his public persona with his homosexuality – wanted to spit in that guy's face.

Second, director John Frankenheimer was completely in love with hippy iconographies and narratives. That at least explains the baffling, overlong nude grape-crushing Bacchanal – you never imagined you'd see so many naked boobs in a movie from the mid sixties.

At first glance (during the opening credits, in fact) it looks like it's going to be a smart, urgent sci-fi thriller for the times. With the psychedelic warping of images of a human face - shifting from intact to shattered in a convex mirror – you realise it's about the nature of identity.

It takes a long time getting itself together, neither the script nor Frankenheimer in a hurry to tell you what's going on. Ineffectual banker Arthur (Randolph) is secretly bored senseless with his quiet life, and although it takes you half an hour of very oblique dialogue that gives nothing away, you learn he intends to be born again.

He visits a company that specialises in second chances, completely remaking their clients through advanced plastic surgery, organising new identities and doing away with the old ones by (in Arthur's case) arranging for his apparent death in a car crash.

Arthur emerges from the recovery as Tony (Hudson), whereupon he goes in search of the sort of freedom he's dreamt about for ages, moving to a mansion in California complete with a butler and falling in with a free spirited neighbour.

From there, the entire rest of the movie until the last scene is one big WTF moment. Tony's apparently still unhappy with his new self – although scenes like the grape orgy and a drunk cocktail party don't make that fact at all obvious.

It's not until he goes back to the company to demand that he get another new identity that things make sense again, turning sinister in a fairly haunting final scene. There are a lot of other ideas and evocative images in there (like the classroom-style chamber full of what it turns out are other clients of the service), but a lot of it is all too far out man to make much sense.

The cinematography and aesthetic approach are crazily compelling several times, you just have no idea what they're compelling you towards. There's also undoubtedly a lot of comment in there about the self and its sacrificing on the altar of markets and consumerism, but it's buried behind a thick layer of what was probably bong smoke.