Under British law, everyone is entitled to fair trial regardless of how morally repugnant and sickening their crime may be.

This presumption of innocence until proven guilty forms the backbone of John Crowley's suspense thriller that starts in an almighty bang with an explosion in a crowded London market.

Soundless CCTV images of the fateful November morning provide a jaw-dropping jolt to pique our interest through the film's exposition-heavy opening hour. Steven Knight's script gets bogged down in legalese and crucially, the pacing is pedestrian, without any noticeable hairpin twists or turns to get the pulse racing once action moves into the courtroom.

An explosion in Borough Market in 2012 shocks the nation and the manhunt begins to unmask the terrorist cell responsible for the atrocity. Only one suspect, Farroukh Erdogan (Denis Moschitto), is captured alive and he prepares to stand trial for his alleged crimes while the public bays for blood.

"The judicial process in this country is and will remain transparent," promises the Attorney General (Jim Broadbent) after he announces that some of the evidence is classified and cannot be seen by the accused or his legal team.

So Special Advocate Claudia Simmons-Howe (Rebecca Hall), a government-approved defence lawyer, is appointed to review this sensitive information and argue for its full disclosure.

From the moment she opens the secret files, Claudia must not communicate with Farroukh or his defence attorney, Martin Rose (Eric Bana), who happens to be her old flame but has kept their relationship secret. With Claudia under constant surveillance by a shadowy MI5 agent (Riz Ahmed), Martin pieces together the truth himself from boxes crammed with files and reports. In the process, he uncovers a grand conspiracy that draws him back to Claudia and jeopardises both the case and their lives.

As opposing forces coalesce around them, Claudia realises that a noble victory is slipping through their fingers.

"We're not strong enough to fight them, are we?" she asks Martin, already knowing his answer.

Closed Circuit feels curiously familiar, uncovering corruption and skulduggery within the corridors of power in Westminster, where one Machiavellian figure menacingly cackles, "Your girlfriend should have kept her mouth shut", within earshot of witnesses.

Australian actor Bana lacks charisma and his British accent frequently returns to the southern hemisphere. On-screen chemistry with Hall, who is solid in an underwritten role, barely simmers let alone boils.

Broadbent chews scenery while Julia Stiles is wasted as a nosy New York Times reporter, who has access to a staggering amount of classified information yet refuses to publish allegations as the truth without evidence.

"You've obviously never read a British newspaper," scoffs Martin, delivering the film's only intentional laugh.