There are some films that can rest solely on the shoulders of a brilliant performance, and Darkest Hour is such a film.

While Christopher Nolan’s Dunkirk places audience in the petrified shoes of soldiers stranded on Dunkirk, Joe Wright’s Darkest Hour focuses on the man who had to decide whether or not Britain would sacrifice those soldiers for a chance at peace with the Nazis.

Taking place during the early stages of World War II, when Britain was facing the possibility that they might not be able to defeat Hitler’s forces, the film looks at the challenges Winston Churchill (Gary Oldman) faced after being appointed Prime Minister. Despite the pressure from former Prime Minister Neville Chamberlain (Ronald Pickup) and other cabinet members to try and broker “peace,” Churchill was determined to fight the Nazis to the very end. However, facing unfavorable odds, and with the eyes of many including King George VI (Ben Mendelsohn) on him, the new Prime Minister faced the difficult decision regarding how much his country would be willing to sacrifice to see this battle to its conclusion.

Darkest Hour is a callback to the historical period pieces that the Academy Award members love so much. An unrecognizable Gary Oldman embodies Churchill and his quirks with great gusto. However, after the glow of the sparkling performance wears off, the lack of depth in the film begins to slowly escape from its cracks.

If this moment in time is meant to provide great insight into Churchill the man, why did I walk away having barely learned anything outside of the fact he was stubborn and wrestled with a tough decision?

One of the most intriguing facets glossed over is the stress that his political life had on his relationship with his wife, Clementine (Kristin Scott Thomas), and children. In fact, most of the women in the film, most notably his new secretary Elizabeth Layton (Lily James) serve no other real purpose than to be cheerleaders for Churchill when he begins to doubt himself.

Not that the male supporting characters fair much better. Wright’s film is so captivated with Oldman’s work, that it never fully allows the supporting players to develop into well-rounded individuals. The closest to come to this level is King George, but even his growth feels out of the blue.

The most surprising thing about Darkest Hour is how, by Joe Wright standards, conventional the film is. His visual eye is still there, capturing the dreary nature of wartime Britain in interesting ways, however, the film lacks the spark and tension that encompassed a film like Atonement. In the end Darkest Hour is merely an adequate film with one phenomenal performance.