On the eve of the graduation parade at Bunker Hill military academy, Cadet Brian Moreland (Timothy Hutton) has a private meeting with the academy's commander, retired Brigadier General Harlan Bache (George C. Scott), who is an esteemed alumnus of the school. During this pivotal discussion, Bache promotes Moreland to Cadet Major, the highest rank achievable at the academy. However, the following day brings troubling news: General Bache, returning home with a weighed-down expression, reveals that the school's board of trustees has agreed to sell the academy to real estate developers. Although the school will remain open for an additional year to allow the Seniors to graduate, this decision instills a mix of hope and despair among the cadets who ponder the potential closure.
Glimmers of normalcy return with an evening dance following the commencement ceremony. Yet, outside the gates, local teenagers provoke a confrontation that spirals into a chaotic brawl. During this turmoil, General Bache intervenes but finds himself disarmed when one of the local boys seizes his service pistol. Tragically, in the ensuing struggle, the gun discharges, resulting in the death of another boy. Although the magazine was removed, a bullet lingered in the chamber, leading to Bache's arrest as he becomes the center of the incident. In custody, he suffers a heart attack, leaving him gravely ill in the hospital; the cadets are distraught as they listen for updates over the police band.
Meanwhile, Dean Ferris and other civilian officials explore the academy's armory, noting the extensive arsenal accumulated over Bache’s tenure. Moreland steps forward, inquiring about the training armaments for the upcoming summer session, only to learn that there will be no summer program and the academy is to be closed immediately, a decision that leaves him incensed. Determined not to give up, Moreland consults his senior officers, and together they resolve to seize control of the campus. When Ferris arrives with the Sheriff to clear out the armory, they are met by a contingent of armed cadets led by Major Moreland, who insist on negotiating with the board of trustees to preserve their beloved school. Overpowered, Ferris and the Sheriff are compelled to vacate the academy grounds as Moreland asserts military command.
In another scenario, a team of cadets dispatched to procure supplies faces trouble when their truck breaks down. As Cadet Captain Dwyer (played by Sean Penn) attempts repairs, local aggressors confront them. Tensions escalate when the impulsive Cadet Captain David Shawn (portrayed by Tom Cruise) reacts by firing his M16 into the air, scattering the locals. However, their foray back results in only half the provisions they originally sought.
The escalating situation draws police to the campus, and a delegation of parents, led by the fiercely military-minded Sergeant Moreland (played by Wayne Tippit), attempts to negotiate peace. In an act of defiance, Moreland rallies the cadets and offers them the chance to leave, but to his pride, they all choose to remain. The arrival of the National Guard intensifies the standoff, and Colonel Kerby (played by Ronny Cox) attempts negotiations but to no avail.
As tensions rise and further confrontations occur, it becomes clear that dissent among the cadets is growing. The following morning brings a disheartening report of fellow cadets abandoning the cause, with even Moreland's friend, Lieutenant Edward West (played by Evan Handler), leading the exit of a significant number of students. Tragedy strikes when the cadets are deprived of electricity and water, leading to a severe burn accident during a desperate attempt to restart a generator. The dire news of General Bache's passing sends shockwaves through the ranks, prompting a poignant military memorial service in his memory.
The following day's events spiral further out of control as military forces prepare to breach the campus. A young cadet panics and inadvertently discharges his weapon, leading to the death of yet another cadet. The inside conflict escalates when Shawn, in a fit of rage, shoots at the guards while Moreland struggles with the mounting pressure. As the authorities overpower the cadets, the session crescendos into chaos with combat resulting in multiple casualties.
In the aftermath of the siege, a montage of historical moments from the Academy’s past plays, serving as a haunting reminder of the pride and struggle inherent within its walls.
