The Whistleblower is a hard-hitting and often sickening expose thriller set in post-war Bosnia. Lead by the superb Rachel Weisz as Kathryn Bolkovac the audience follow a gripping true-life story that unfortunately doesn’t quite get the big-screen outing it deserves.

The Whistleblower is not short of drama or tension but debut director Larysa Kondracki’s attempts to show Bolkovac’s plight in an area riddled by sex-trafficking are not always completely successful.

Bolkovac is a Nebraskan police officer looking to transfer to be closer to her daughter. But instead she ends up taking a well-paid UN-contracted peacekeeping job; leading to the shocking discovery of just how involved her own colleagues are in a brutal tale of corruption and cover-ups.

The highlight of the film is undoubtedly Weisz who is mesmeric as strong-willed and professional Bolkovac. On paper Weisz is supported by big-name stars Vanessa Redgrave (as head of the Women's Rights and Gender Unit Madeleine Rees) and David Strathairn (as Internal Affairs officer Peter Ward) but these characters get criminally underused throughout the film.

Whilst Weisz is fantastic, the concentration on her character Bolkovac means the story often limps in duration, too often lacking the punch such a dramatic subject matter deserves.

But to this film’s credit Director Kondracki does master the upsetting human side of the tale. This is most notable through crossing to the lives of two young Ukrainian girls. Scenes focusing on the young girls stuck in this most hideous of crimes are probably the hardest to watch but definitely the most powerful.

Weisz’s inclusion alone is enough to warrant watching The Whistleblower but you will probably only ever need to watch this film once - both due to the film’s failings and terrifying journey.