CAPTAIN AMERICA: CIVIL WAR (12A)

Directors: Joe Russo, Anthony Russo.

Starring: Chris Evans, Robert Downey Jr, Scarlett Johansson

THE fragile alliance between the Avengers is shattered in the third Captain America film, directed at a breathless pace by brothers Joe and Anthony Russo.

Opening with a flashback to 1991 that sets one major character on their self-destructive path, Civil War underscores its bombastic title by pitting former allies against each other in a series of dizzying showdowns that cleave apart the Marvel Comics universe.

Scriptwriters Christopher Markus and Stephen McFeely repeatedly inhabit the blurred lines between heroism and villainy, examining the moral conundrums faced by super-powered warriors who have pledged to protect the innocent from the righteous crossfire.

Alas, no one emerges unscathed from the melee and the deep psychological wounds inflicted in these bombastic 147 minutes suggest that this muscular chapter signals a bittersweet end for some characters while blatantly teeing up standalone spin-offs for Spider-Man and Black Panther.

A year has passed since the events of Avengers: Age Of Ultron and the US Secretary of State Thaddeus Ross (William Hurt) insists on the introduction of legislation – The Sokovia Accords – to control the superheroes.

Tony Stark's Iron Man (Robert Downey Jr) reluctantly submits, telling his compatriots: "I'm doing what has to be done to stave off something worse."

Steve Rogers' Captain America (Chris Evans), who has always been a staunch patriot, refuses to sign, fearful of the consequences of the Avengers relinquishing their independence.

The gulf between Stark and Rogers forces the remaining Avengers to take sides.

Black Widow (Scarlett Johansson), War Machine (Don Cheadle), Vision (Paul Bettany), Black Panther (Chadwick Boseman) and Spider-Man (Tom Holland), making his debut in the Marvel cinematic universe, all stand shoulder to shoulder with Stark.

Meanwhile, Winter Soldier (Sebastian Stan), Falcon (Anthony Mackie), Scarlet Witch (Elizabeth Olsen), Hawkeye (Jeremy Renner) and Ant-Man (Paul Rudd) pledge their allegiance to Rogers.

A battle royale between the two factions unfolds just as a diabolical new enemy, Baron Zemo (Daniel Bruhl), threatens mankind.

Captain America: Civil War could easily trim 20 minutes from its bloated running time without diminishing the impact of the special effects sequences or the pivotal plot twists.

The Russo brothers choreograph destruction on a grand scale, including an adrenaline-pumping motorcycle chase on the rubble-strewn streets of Berlin.

Evans and Downey Jr puff out their chests for supremacy in every lavish frame, while Johansson somersaults sexily between the feuding factions.

A protracted sequence involving Stark, a nerdy Peter Parker and Aunt May (Marisa Tomei) sows seeds of hope that next year's reboot, Spider-Man: Homecoming, might revitalise the web-slinging vigilante with whip-smart humour.

Miracles might happen.