During a thunderstorm in early September 1944, units of the 35th Infantry Division are nearing the French town of Nancy. One of the division's mechanized reconnaissance platoons is ordered to hold their position when the Germans counterattack. The outnumbered platoon also receives friendly fire from their own mortars.

Private Kelly (Clint Eastwood), a former Lieutenant scapegoated for a failed infantry assault, captures Colonel Dankhopf of Wehrmacht Intelligence. Interrogating his prisoner, Kelly notices the officer's briefcase has several gold bars disguised under lead plating. Curious, he gets the colonel drunk and learns that there is a cache of 14,000 gold bars, worth US$16 million ($230 million today), stored in a bank vault 30 miles (50 km) behind enemy lines in the town of Clermont. When their position is overrun and the Americans pull back, a Tiger I kills Dankhopf.

Kelly decides to go after the gold. He recruits Supply Sergeant "Crapgame" (Don Rickles) in order to obtain the supplies and guns that will be needed. A spaced-out tank platoon commander known as "Oddball" (Donald Sutherland) overhears, and he and his three M4 Sherman tanks join the caper. With their commanding officer, Captain Maitland (Hal Buckley), preoccupied pursuing opportunities to enrich himself, the men of Kelly's platoon are all eager to join him. After much argument, Kelly finally persuades cynical Master Sergeant "Big Joe" (Telly Savalas) to go along.