Gary Oldman is Winston Churchill.

Many actors have portrayed the famous British bulldog—most recently John Lithgow in his Emmy-winning turn in The Crown—but none have so completely disappeared into the role as Oldman. The transformation is so complete that we instantly forget we’re watching an actor when Churchill first pops up onscreen. Oldman’s Churchill, in contrast to many portrayals, isn’t a curmudgeonly old dodder, but a spry, even youthful, 65-year-old man who is full of vigor and zeal. He almost always has a sparkle in his eyes and a buoyancy in his step. But he’s also flawed and crippled with doubt when the prime ministership is thrust upon him.

Darkest Hour recounts roughly Churchill’s first month in office, May 10 to June 4 of 1940. The war in Europe is already underway and the Nazis control France. The Germans intend to conquer England, which is more vulnerable than ever since more than 300,000 Allied troops are trapped on the beach at Dunkirk. Weak-kneed prime minister Neville Chamberlain (Ronald Pickup), who hopes to somehow accommodate Hitler by bargaining with him, is forced to resign. The polarizing and unpredictable Churchill replaces him. But from the get-go, Churchill faces dissent within his own party, while the opposition is eager to force his ouster and supplant him with the more appeasing Viscount Halifax (Stephen Dillane). Even King George VI (Ben Mendelsohn, reticent and regal) disdains him.

Fortunately, Churchill gets great support at home from his strong-willed wife Clemmie (a resplendent Kristin Scott Thomas), and from the British people themselves, who are unaware that their leader sometimes lies to them to protect them from the dire truth of the dilemma facing their country. In what is perhaps the film’s most contrived but effective scene, the great man hops out of his chauffeured car, which is mired in traffic, and makes his way to an underground train. Onboard are ordinary citizens. Churchill, who is conflicted over whether to retreat from war and thus put British sovereignty in jeopardy, or to forge ahead into a battle that is certain to be bloody and perhaps calamitous, puts the passengers at ease through a bit of self-deprecation and then gives them the floor. It soon becomes clear they would rather fight and even die than be ruled over by the tyrant Hitler. Churchill then knows what he must do.

Screenwriter Anthony McCarten’s incisive script revolves around three of Churchill’s most famous speeches: his initial address as prime minister to the House of Commons, his first radio address to the British people, and finally the “We shall fight on the beaches” speech that roused his people to war. McCarten, along with director Joe Wright (Atonement, Pride & Prejudice), takes us deep inside the smoky war rooms, the boisterous hallways of Parliament, and the stately accommodations of 10 Downing Street and Buckingham Palace, where the private and political battles that determined the eventual fate of Europe were waged and won. It’s riveting stuff.

None of this would be nearly as effective, however, without Oldman’s towering performance at the film’s center. If ever there was a man destined for his time it was Winston Churchill, and if ever there was an actor destined for a role it’s Oldman in Darkest Hour, who should start clearing a space on his mantel for some serious Oscar hardware come the new year.