For two thirds of its running time, Derek Cianfrance’s tale of a blue collar drifter and an underachieving, mollycoddled beat cop, one tagging the other en route to what should have been the story’s natural end, can have its pick of the superlatives. It’s engrossing, compulsive, mesmerising, honest and well acted, albeit with a sobriety that’s award baiting. There’s not been a better film all year. Then it happens; that third act. It’s a self-indulgent bit of vandalism; a long and unnecessary coda that adds a ruinous streak of contrivance to what had been a tightly focused and beautifully judged affair.

What will Cianfrance tell himself when he reviews his work many years hence, whisky bottle in hand, and sees past the ambition to the reality: the soap opera, the plot contortions, the wince inducing implausibility? He might argue this was always the grand design – ‘fathers and sons’ he’ll say, that’s what it was all about, but surely there was another story being told here, a better one, and the tragedy for audiences gripped by the red-raw and intimate movie that precedes the collapse, was that he’d told it and told it well. One snip of the editor’s scissors would have assured the film’s reputation. Instead, a blue-balled audience ends its evening mired in lethargy and frustration. You’re reading this review, you know the feeling.

The story that had been told, and successfully, was that of travelling stunt rider Luke, played with smouldering intensity by a rough and ready Ryan Gosling. Luke’s a loner; the kind of independent American movie archetype who says little but communicates much using a glare. Gosling, body plastered with tattoos, moth eaten t-shirts worn inside out, is such a perfect fit for this kind of role that he could quit acting tomorrow and declare job done. He’s James Dean with extra muscle; a danger man who’s buried his inner-turmoil so deep that it’d take a mining crew to reach the periphery, yet in the 45 minutes we have with him we see the vulnerability, the steel; the guy who turns to bank robbery so he can provide for a son he’s only just met. “My Dad wasn’t there for me and look how I turned out” he tells baby mother, Eva Mendes, and therein lies the seed that grows into the hideous and unkempt final third, but it also lights the blue touch paper for the second part, the act in which Bradley Cooper’s plod, a straw man who dreams of being human, also with a young son in tow, is drawn into a criminal enterprise and is morally tested. What follows is better than anything in the third act; proof that movies can be botched in conception yet still be great, provided the filmmakers recognise excrescence and prune accordingly.

Cooper’s story works because it’s both the logical continuation of Gosling’s and stacked with dramatic red meat: parallels and lip-licking contrasts. It has something to say about two very different men, one uneducated and abandoned, the other a well-off graduate and son of a public official, whose lives briefly intersect. It is, as they say, biblical. An honest criminal is contrasted with a dishonest law enforcement officer. Life conspires to ruin the reputation of the man who was determined to be close to his son, while granting great success to the man who ultimately alienates his. It’s rich and its enough, so why the 40 minutes that relocates Midnight’s Children to Schenectady, New York? What was to be gained? Pathos, you say? Tar-thick irony? Well maybe, but I liked this movie better when it had some purchase on reality. Biblical plot twists played better in days of yore. We’re acutely aware of plot in an overplotted age and we know when it’s over played its hand.

The failure of the final third is not attributable to Dane DeHann or Emory Cohen; both give measured performances as the sons of Gosling and Cooper, commensurate with what’s come before, it’s just their bad luck to be part of a superfluous concluding episode; the proverbial water in the whisky.

The economically plotted crime drama that opens The Place Beyond the Pines, with brooding photography that establishes and maintains a grungy sensibility, is worth the price of admission alone; Gosling’s magnificent in what might be his best performance. This act is taut, visceral and exciting. The police corruption story that follows is gripping and nuanced; a fine companion for the first part. Faith No More’s Mike Patton provides a haunting piano and string accompaniment. I’m going to do what Derek Cianfrance should have done and end the story there, recommending you duck out at the 110 minute mark and don’t look back.