How do you fight an un-winnable war? Surely it’s a bit like that age old puzzler that Iain Banks raised in his novel Walking on Glass. In the book, he posed the question: ‘What happens when an unstoppable force meets an immoveable object?’. The answer he gave was that the unstoppable object stops and the immovable object moves.

In Sicario (a word meaning ‘hitman’ in Spanish), the unstoppable force takes the form of the Mexican drug cartels – an affiliation of ruthless gangsters who are directly responsible for the continually escalating violence and murder in an effort to protect their lucrative trade and ensure a steady supply across the border to the “20% of Americans who consume drugs daily”.

However, the very fact that the appalling violence that taints Mexican streets on a near daily basis is now spilling across the border into the good old US of A is what compels the formation of an elite task force in an effort to combat this disturbing trend. Matt Graver (Josh Brolin), who heads up the operation, is responsible for recruiting agents to this task force which results in an idealistic FBI agent called Kate Macer (Emily Blunt) being brought to his attention.

The reason this occurs is outlined as the movie opens, where we are given an intimate insight into the nature of the operations that Kate performs with her FBI ‘clean up’ squad as they carry out an investigation of a house near the Mexican border which is suspected to be related to cartel activity. A short time after this tense encounter, Kate is introduced to Matt Graver and asked if she wants to make a real difference to this bloody, never-ending drug war by joining the team on a voluntary basis.

One of the early missions she is asked to act as an observer on brings her into contact with a shadowy figure called Alejandro (Benicio Del Toro) who is terse and non-committal when questioned by Kate as to his role in the operation. However, this is far from her only concern as during the team’s first operation to escort a key Mexican prisoner across the US border, a tense stand-off arises at the border point which not only results in bloodshed but also causes Kate to question what exactly the group is trying to achieve. Their seemingly ‘carte blanche’ violent approach to dealing with any opposition to their plans results in Kate furiously confronting Matt Graver about the group’s true objectives.

Sicario is very much a study in morality, justice and vengeance. It is an elegant character portrayal of two key opposing figures. Kate represents a sense of ordered morality and justice – someone who is willing to follow due procedure and legal channels as much as possible. However, she becomes troubled and conflicted due to what she experiences during the course of the movie while part of this dubious operation she volunteered for.

On the opposite side of the chess board, sits the mysterious Alejandro, whose true role and motives are revealed as the film progresses. His world is very simple: he is willing to work for the US goverment because it gives him license to hunt down his enemies and exact revenge. Kate’s ordered world is thrown into chaos as she tries to comprehend how a government agency could recruit such a shadowy, morally dubious individual.

To the audience, it probably makes a lot of sense but to Kate it represents getting into bed with the devil. Matt Graver asks her the question: how do you expect to win this war using the same weak, bureaucratic methods for years on end? They’re ineffective, he argues. To bring the devil to his knees, you not only have to know his methods intimately, but ultimately be prepared to use them against him.

Sicario is a tense thriller, meticulously shot and laden with stark, disturbing imagery. What stops it from being a movie that is too difficult to endure are some truly outstanding performances. Del Toro steals the show again as a man who can say more with one slightly raised eyebrow than several other so-called A-list actors can manage with a mountain of dialogue.

Emily Blunt at first looks like someone completely miscast in such a traditionally masculine role but it is to her credit that she not only makes the role believable but completely owns it as well. Clearly, the writers and director were trying to subvert a well-defined stereotype and it is because Emily Blunt is such a skilled and capable actress that she manages to do this admirably and convincingly.

Credit should also be given to the supporting cast, especially Daniel Kaluuya who plays Kate’s partner Reggie Wayne. He’s a mistrusting but loyal friend to Kate who accompanies her as she is drawn further and further into this murky and dangerous world.

This is a significant movie in many ways as it asks some important questions not only about human nature but also government motives and methods in fighting such a brutal, complex and seemingly never-ending drug war.  More importantly, it is prepared to ask difficult questions about what drives us and makes us human. Is it our sense of morality, our sense of right and wrong or is it something deeper, something that is at the core of each and every one of us…?