Nasty, tasty police drama which creates an unusually brutal picture of the capital's criminal gangs. Nigel Patrick is an old school senior copper who operates by immersing himself in the underworld and doesn't play by the rules. But gets results. His boss (Harry Andrews) wants him to clean up his act and employ modern police methods.
When Patrick's main informer turns up dead, he follows the snout's final lead to a ruthless mob of bank robbers. They are fronted by a flash, vicious psychopath (Derren Nesbitt) but led by a quiet, more considered organiser (Frank Finlay). Nigel is compelling as the cool, street smart inspector. And Nesbitt tears up the scenery to knockout effect.
The plot is a quick shuffle of Fritz Lang's classic noir, The Big Heat, but the feel of the film looks forward to The Sweeney. The cops are just another London gang and not always honest. The crooks get caught because they are dim gamblers who can't play a long game, and cheat each other. Senior police are politicians with a clean profile. The public has to take their chances.
The only bum note is a big gangland punch up towards the climax. Ken Annakin directs with uncharacteristic panache. It's too late for film noir but the interiors have that look. It's the sort of British crime film where the crooks hide out in a lockup in the East End. It's a thrilling, raw, violent gangster film with a foul villain and a nonchalant, charismatic hero.