Operation Market Garden envisages 35,000 men being flown 300 miles (480 km) from air bases in England and dropped behind enemy lines in the Netherlands. Two divisions of US paratroopers are responsible for securing the road and bridges as far as Nijmegen. A British division, under Major-General Roy Urquhart, is to land near Arnhem and hold both sides of the bridge there, backed by a brigade of Polish paratroopers under General Stanislaw Sosabowski. XXX Armoured Corps are to push up the road over the bridges captured by the American paratroopers and reach Arnhem two days after the drop.

As General Urquhart briefs his officers some of them are surprised they are going to attempt a landing so far from their objective since the distance from their landing zone to the bridge will render their portable radios useless. Although the consensus is that resistance will consist entirely of inexperienced old men and Hitler Youth, reconnaissance photos show the presence of German tanks at Arnhem. General Browning nevertheless dismisses the photos and also ignores reports from the Dutch underground, believing the operation will be successful regardless.

The Arnhem bridge is the prime target, since it serves as the last means of escape for the German forces in the Netherlands and a direct route to Germany for the Allies. However the road to it is only a single lane linking the various key bridges and vehicles have to squeeze onto the verge to pass. The road is also elevated, causing anything moving along it to stand out.

Though the airborne drops catch the enemy by surprise and encounter little resistance, the Son bridge is demolished by the Germans just before it can be secured. Furthermore, troubles beset Urquhart's division, since many of the jeeps either do not arrive or are destroyed in an ambush, in addition to their nonfunctional radio sets.

Meanwhile, XXX Corps' progress is slowed by German resistance, the narrowness of the road and the need to construct a Bailey bridge to replace the one destroyed at Son. They are then halted at Nijmegen, where soldiers of the 82nd Airborne Division perform a dangerous daylight river crossing to capture the Nijmegen bridge and XXX Corps is further delayed waiting for infantry to secure the town.

The Germans close in on the isolated British paratroopers occupying part of Arnhem at the bridge, and although Sosabowski's troops finally arrive after being delayed in England they are ultimately too late to reinforce the British. After days of intense fighting against SS infantry and panzers the outgunned troops are eventually either captured or forced to withdraw to Oosterbeek. Urquhart receives orders to retreat, while the other Allied commanders blame the various difficulties encountered for their failure to provide the needed support.

Urquhart escapes with less than a fifth of his original ten thousand troops while those who are too badly injured to flee stay behind to cover the withdrawal. On arrival at British headquarters Urquhart confronts Browning about his personal sentiments regarding the operation and the latter contradicts his earlier optimism regarding it.

Back in Oosterbeek Kate ter Horst, whose home has been converted into a makeshift hospital by the British, abandons its ruins. Passing through the front yard, now a graveyard for fallen troops, she and her children leave with an elderly doctor, pulling a few possessions in a cart, while wounded British troops sing "Abide with Me" as they await capture.