The film opens by illustrating the intense challenges faced by the Allies in their battle against U-boats targeting their freighters. We transition to a scene onboard the submarine U-571, which successfully torpedoes and sinks a freighter. The crew celebrates their success, but their joy is short-lived when the sonar operator detects a destroyer approaching at high speed. In a rush, the Captain orders the submarine to dive to evade the incoming threat.
As the destroyer unleashes depth charges in pursuit, U-571 suffers a catastrophic fuel line rupture, igniting a fire in the engine room. In the chaos that follows, the Captain learns from Chief Harvey Keitel that their batteries are nearly depleted, the diesel engines are out of commission, and all engineering personnel have perished. Recognizing the dire situation, he instructs his radioman to send out an Enigma-encoded SOS for assistance.
Meanwhile, onboard the United States Navy submarine S-33, crewmen are celebrating the wedding of Crewman Larson when Lt. Andrew Tyler, portrayed by Matthew McConaughey, enters, visibly troubled by the denial of his own command. Following a heated discussion with Lt. Commander Dahlgren, Tyler learns that he has been passed over for promotion. Just then, Military Police intrude to announce an urgent mission, abruptly ending their shore leave.
Upon arrival at the base, the crew is shocked to find the S-33 being modified to look like a German U-boat, complete with German uniforms. Naval Intelligence officer Hirsch enlists Tyler’s help to find Radioman Wentz, who has proficiency in German due to his family background. Alongside a Marine named Coonan, who arrives with explosives, the stage is set for an audacious plan: to masquerade as a resupply ship for the stricken U-571, capture its precious Enigma machine, and scuttle the submarine.
Despite Tyler's skepticism about the mission's success, he conforms to orders. Back on U-571, the Captain makes a grim decision to execute survivors from the merchant ship he previously sunk, adhering to orders to eliminate all witnesses.
Eventually, amidst a storm, the S-33 locates U-571 and sends a boarding party—led by Coonan—onto the German submarine. Here, Wentz's torn identity comes to the fore as he struggles to maintain their cover. Initially, the Germans welcome the Americans, but chaos ensues when a midshipman detects the American weaponry, leading to a furious exchange of gunfire. The Americans, demonstrating unmatched resolve, bravely take control of the U-571, seizing the Enigma and capturing the crew, including their Captain.
As the prisoners are shuffled between ships and preparations are underway for scuttling the U-571, a harrowing twist occurs; the real German supply submarine surfaces and launches a torpedo, striking the S-33. Wounded and struggling, CO Dahlgren instructs the crew on the U-571 to submerge and save themselves. This pivotal scene is rooted in the real-life events of World War II. Tragically, several crew members are lost, forcing Tyler to step up and lead the commandeered submarine.
Now facing overwhelming odds, the crew fights desperately to disarm the charges placed on their vessel. With the language barrier complicating things, only Harvey Keitel and Wentz can read German, and as they engage in a frantic battle of wits, they successfully fire some torpedoes, profoundly damaging the pursuing German submarine. With their resources dwindling and the last torpedo loaded in a malfunctioning tube, the atmosphere aboard grows tense.
While searching for survivors, the team discovers two individuals: Eddie, the S-33's cook, and an enigmatic German sailor posing as an electrician, who is in fact the Captain of U-571. As the crew hastily repairs one of the diesel engines, Tyler makes a bold decision to return to England, despite dissent among the men. When the German Captain breaks loose and causes chaos, Tyler is forced to maintain order, emphasizing the importance of the Chain of Command.
In a gripping turn of events, Tyler orders a shot fired from the deck gun to cripple the enemy destroyer, sparing their own lives. When it comes to a climax, U-571 faces the brutal tactics of depth charges from the destroyer, pushing the submarine to its limits beneath the crushing pressure.
In this high-stakes environment, Tyler orders Trigger to sacrifice himself in a critical maneuver. As the crew makes a triumphant final strike against the destroyer, they mourn the loss of two teammates, realizing the heavy cost of war. Ultimately, U-571 finishes its mission, surrendering to the depths as they barely escape, clutching the Enigma machine. Floating in a lifeboat, the crew’s hopes are lifted when spotted by a U.S. Navy seaplane, hinting at a fragile victory amidst the backdrop of sacrifice and resilience.
