There was a stretch of time recently when violent, talky crime stories flourished in the British film scene like mushrooms in a woodland glade. Lock, Stock and Two Smoking Barrels, Sexy Beast and Bronson are some of the more successful exercises in the genre. But then there’s a lot of inedible fungus in there too, several of them featuring now eminent talents such as Ray Winstone (44 Inch Chest), Jude Law (Breaking and Entering), or both (Love, Honour and Obey).

Before he was canonised as one of Britain’s finest thespians, Gary Oldman made several contributions to this mycological mulch. With Killers Anonymous he returns to these soggy roots, contributing a turn as an assassin’s agent who runs a 12-step programme in Los Angeles for people who kill repeatedly. It’s a nonsensical premise and a pretty incoherent, painfully inept film. Despite being prominently featured in the credits, Oldman is quite peripheral to the action after the opening two scenes and he ends up spending much of his screen time sitting alone on a roof watching the action from afar.

The rest of this lurching ensemble piece revolves around a supposed meeting of a London chapter of Killers Anonymous, chaired regularly by Joanna (MyAnna Buring), a vicar with a murderous streak. Other members of the chapter include Tim McInnerny as a creepy Harold Shipman-like doctor, Elizabeth Morris as a tough-talking thug, and Michael Socha as a more soulful participant who reaches out to mysterious newcomer Alice (Rhyon Nicole Brown) when he senses that her frightened demeanour doesn’t seem to go with the group’s raison d’etre. An explanation is eventually forthcoming, but that doesn’t excuse the tottering tedium one is required to endure. This will be one title that few of the participants will want included on their bios.

• Killers Anonymous is released in the UK on 26 August