A long time ago, in a galaxy far, far away …

Here we are once again, back in the space opera as imagined by George Lucas, but this is a world much darker than last year's The Force Awakens.

Set between the 2005 prequel Revenge of the Sith and the events of the 1977 original A New Hope, the story revolves around Jyn Erso as played by Felicity Jones. A criminal in the eyes of the Empire, she watched her father (Mads Mikkelsen) being led away by the fearsome all-black death troopers as a child.

A new hero joins the band of rebels and strikes a defiant tone. From left to right, Cassian Andor (Diego Luna) and Jyn Erso (Felicity Jones). (Giles Keyte/Lucasfilm)

As an adult, she hides behind a shield of apathy. Politics is a luxury when you're focused on survival. But when Jyn learns that the fate of her father is tied to the Empire's new weapon, she joins the nascent Rebel Alliance and is soon making the case for a desperate long shot: a raid on an Imperial base to capture the Death Star plans.

A grim hero

As Jyn, Jones gives us a battle-hardened hero in the mould of Han Solo, but without the rakish charm. It seems life under the boot of the Empire has ground out much of her humour. Her unending reserve of furious determination can get tiring after a while, but she's complemented by a colourful band of outlaws:

Diego Luna as Capt. Cassian Andor, who carries the burden of keeping the rebellion alive at any cost.

Donnie Yen as a mystic monk who is blind but strong in the ways of the Force (and watch out for that staff).

Riz Ahmed as Bohdi, an Imperial pilot looking to make amends for aiding the Empire.

The rebel alliance debates how to respond to the Empire's massive new weapon. From left to right, the characters Mon Mothma, Cassian Andor, General Draven and Dodanna. (Lucasfilm/ILM)

Another memorable convert to the cause is the reprogrammed Imperial security droid K-2SO, brought to life by Firefly's Alan Tudyk. K-2SO is insolent, easily bored and has trouble following orders. R2-D2 would be proud.

Malevolent Mendelsohn

Of course, any hero's journey is only as good as its villain, and here we're well-served by Ben Mendelsohn as the Death Star construction director Orson Krennic.

With roles in Mississippi Grind or the series Bloodline, Mendelsohn has built his career playing a wonderful string of wretches. As the vain, simmering commander Krennic, Mendelsohn slips easily into the Imperial uniform.

Martial arts star Donnie Yen appears as the mystic Chirrut Imwe, who takes on a squadron of storm troopers with a single staff. (Lucasfilm/ILM)

In an early scene where he argues with Jyn's father, Galen, about building the Death Star, he talks of bringing order to the galaxy.

"You're confusing terror with peace," says Galen, to which Krennic sneers, "You have to start somewhere."

The casualties of war and the compromises made along the way are the terrain that director Gareth Edwards is exploring here. Rogue One has all the Star Wars staples: the spine-tingling space battles, the John Williams-like score, but there's an added level of grittiness to the action.

Vain and villainous, Ben Mendelsohn stands out as the Death Star construction director Orson Krennic. (Giles Keyte/Lucasfilm)

Star Wars meets Saigon

Watching X-wing fighters swoop over palm trees or safari-coloured storm troopers engage in urban combat, you might not be surprised to learn Edwards won over Disney by pitching Rogue One as a Vietnam-style story.

Of the recent Star Wars films, this is the first that has an echo of wars we've witnessed. There's a moment during a skirmish in a holy city where Jyn spots a child alone and screaming in the middle of a storm trooper gun battle, a striking image that could easily be taken from Saigon or Syria.

Rebel forces battle the Empire as AT-AT combat walkers approach in a scene from Rogue One. (Lucasfilm/ILM)

In a way, Rogue One's greatest weakness is also its strength. Although the story dovetails elegantly into the events of Episode IV, this is a film that has to succeed on the strength of its own original merits. Sure, there's a toy box of cameos for the fans, but no major characters to save the day. No Luke or Chewie or swooping Millennium Falcon to give us the warm fuzzies.

While we don't have the same nostalgic attachment to Cassian, Bodhi and Jyn, that's what unburdens Rogue One, giving it a freedom to tell a story on its own terms.

A band of heroes drawn together for different reasons. Cassian Andor and Jyn Erso are joined by the reprogrammed security droid K-2SO. (Jonathan Olley/Lucasfilm)

At the end we're back where it all began. Yes, with a new sense of hope, but also of the cost.

RATING: 4 out of 5 stars