My drug buddy: "Limitless"

Neil Burger's tricksy thriller Limitless opens with professional smirk merchant Bradley Cooper perched on the ledge of his penthouse apartment, looking down at a Manhattan sidewalk some hundred or so floors below him. Once the audience's clamorous cries of "Do it! Jump, man!" have died down, we settle into the tale of a loser scribe (Cooper) and his troubled relationship with the experimental drug that has brought him to this brink. The mind-expander in question - "NZT-48", as pushed by a shady brother-in-law - has the immediate benefit of clearing our hero's writer's block, bestowing money, women and success upon him, even restoring relations with his ex Abbie Cornish. Nobody's told him about the side-effects, though: paranoia, a shortened attention span, and a tendency to find oneself pursued around the city's streets by narky Russian loansharks.

The role is practically tailored to the experiences of an actor whose wildest dreams must have come true after years in the wilderness. Cast because he's hot (and, presumably, still relatively cheap with it) Cooper proves generally more convincing as a self-deluded no-hoper than as the megabrain spouting forth on algorithms and "Aunt Helen's tumour", at which moments he starts to radiate the glib insincerity that has made his recent rise to prominence so problematic. Add to this another variably interested Robert DeNiro performance ("I'm moving out of the energy business," his powerbroker declares at one point, inadvertently summing up the last fifteen years of the actor's career), and some dull business about deal restructuring that appears to have been added at the behest of Richard Branson's relaunched production company Virgin Films, and Limitless really ought not to work.

What keeps it on just the right side of watchable is the very capable direction. After the genteel period trappings of 2006's The Illusionist, Burger here strains with every frame to make cinematic the highs and lows of drug abuse, culminating in a remarkable effect that turns one of Cooper's wilder nights on the town into a single, uninterrupted stream of visual data. The script demurs and gets messy on the matter, but the director, at least, never quite loses sight of the consequences of all this consumption. However flashy the thriller structure, a fascinated attention is paid throughout to such details as the leads' skin tones; these junkies actually look like junkies when their situation calls for it. The film isn't remotely in the same league, but it may be the most dynamic job of directing under the influence since Danny Boyle tackled Trainspotting.

Limitless opens nationwide tomorrow.