Sergeant Stan Boyle (William Bryant) loads up his handgun during the early hours of the Seattle morning and sets out on his business. But his mission is not police business, it's to murder two cops in cold blood, which he carries out with ruthless efficiency. He then visits a nearby diner for a glass of milk until his contact drives up; going to meet him and dropping off a slipcase, Stan doesn't realise the next man on the hitlist is himself. Later, cop on the verge of retirement Lon McQ (John Wayne) wakes up to hear the news his partner is in a critical condition - and someone wants McQ to join him...
It was only natural that the most famous star of westerns, John Wayne, should end up by the seventies in that decade's equivalent of the genre (contemporary westerns falling by the wayside by then): the urban cop thriller. Swapping his horse for a snazzy motor, it was a disillusioned landscape Wayne was making his way through, where corruption had soured the much-vaunted American Way and he was looking out of date as the one man, an elderly gent you can't help but notice, standing up to the forces of evil.
Wayne was apparently disappointed with himself that he turned down the Clint Eastwood role in Dirty Harry, so this was his production company's answer to that hit, bringing in veteran director John Sturges to head the filming. However, McQ less resembles the original Dirty Harry than one of the sequels, where the character was fast becoming a cliché and Wayne didn't do much to dispel the feeling that there was an already hackneyed air to the film's plotting and second hand heroics.
Detective Lieutenant McQ knows he's a target of whoever was after those cops when a recognised hitman takes a shot at him as he strolls off his houseboat that morning, but he's enough of a man to blow the criminal away without a moment's thought - self defence, of course. He's still troubled by this turn of events, mind you, and wants to be put onto the case, but his boss, Captain Kosterman (Eddie Albert) is reluctant. Does this stop the big man? No it does not, and before long he has tracked down the conspiracy to drugs lord Santiago (Al Lettieri), who he helpfully beats up in a public lavatory.
But there's more to this than an upstanding member of the community like McQ realises, and as he gets swamped by the machinations of a corrupt police force he is in over his head. For a while, anyway, as the film becomes bogged down in scenes of Wayne interviewing various characters (see him at the nightclub for a real fish out of water), never connecting with a pulse pounding paranoia that might have made this exciting: Wayne just wasn't that kind of star and it's odd to see his black and white morality clash with shades of grey. To compensate, there are decent quality action sequences, especially the finale where McQ gets to use that machine gun he's been carrying around for half the movie. Yet for the most part this is like a seventies television pilot in widescreen - it's no Brannigan, that's for sure. Music by Elmer Bernstein.