Sometimes real-life tragedy can sabotage even the most cartoonish crime thrillers. A heavily fictionalised depiction of the undercover police team who helped bring the notorious Los Angeles mafia boss Mickey Cohen to justice at the end of the 1940s, Gangster Squad was partly reshot last year following the massacre at the premiere of The Dark Knight Rises in Aurora, Colorado. A movie--theatre gun battle scene was replaced with a fiery showdown in LA’s Chinatown, and the film’s release was pushed back several months. All the same, Gangster Squad remains deliriously, extravagantly violent in its machine-gun street fights and explosive car chases. Josh Brolin plays the strait-laced, two-fisted leader of the guerrilla detectives and Ryan Gosling is his suave, silver-tongued, womanising sidekick. Meanwhile, Sean Penn finally gets his Raging Bull moment, donning heavy make-up and shamelessly overacting as the former prizefighter turned megalomaniac mobster Cohen. Will Beall’s script claims to be inspired by real events but it owes less to the history books than to the overblown melodrama and crudely drawn morality of comic strips, pulp thrillers and old-school Westerns. That said, the director Ruben Fleischer’s flashy, splashy underworld epic looks and sounds fantastic with its jazzy score, sumptuous art deco interiors, gorgeous clothes and meticulously recreated retro Hollywood vistas. Every frame has been digitally tinted in the warm pastel shades of vintage postcards. The sharply dressed, sleazy glamour of LA’s post-war criminal underworld has been seen on screen many times before, most memorably in Curtis Hanson’s 1997 Oscar-winning LA Confidential. Indeed, Cohen popped up as a character in Hanson’s film and several others, including Warren Beatty’s Bugsy. But Gangster Squad harks back to an older and more simplistic Hollywood tradition of square-jawed lawmen heroes, diabolically evil mobsters and sultry femme fatales. It also contains fleeting homages to superior crime classics such as Chinatown and Miller’s Crossing. But the movie it borrows most from is Brian De Palma’s bubblegum blockbuster The Untouchables, in which a tight gang of specially trained supercops bring down a notorious real-life mafia boss. Given the heavyweight talents involved, Fleischer’s slam-bang crime saga sets the IQ bar disappointingly low with its dumbed-down celebration of macho gun violence and all-American vigilante justice. The male characters are two-dimensional at best, while their skimpily sketched female counterparts are barely allowed one each. Even so, if you can forgive its knucklehead values and predictable genre limitations, Gangster Squad is a highly exciting roller-coaster ride of stylised nostalgia and supercharged action. A very guilty pleasure. The National .