We meet Robert Jordan and learn of his mission to blow up the bridge. He meets Pablo's guerilla band, wins over Pilar and commits them all to his mission. He and Maria fall in love. The next day, he and Pilar recruit El Sordo to the operation. All the forces needed are gathered.
Things take a bad turn. A snow storm screws El Sordo, whose band is destroyed the next day. The peeps grow more pessimistic about the mission. It starts to look as if the Republican offensive has been anticipated by the fascists, and Andrés is dispatched to try and stop it. Escalating tensions with Pablo culminate in his stealing the detonators.
Pablo returns with more men. Andrés reaches Golz, but is too late to stop the attack. The offensive begins, and the guerillas take the sentry posts around the bridge and blow it up, some dying in the process. Robert Jordan is wounded in the escape attempt and left behind to buy his fleeing friends some time.