Lieutenant Nikolay Pluzhnikov tours the city with another traveler, a Jewish woman named Mirra, who serves as a cook in the officer's canteen.
He, Mirra, and a group of soldiers under his command begin defending the Brest Fortress, in spite of extremely unequal odds.
Although the small, inexperienced force of Soviet soldiers in the opening hours of the battle were stunned by the surprise attack, running short of supplies, and cut off from the outside help, many of them held out much longer than the Germans expected.
The defenders are slowly pushed back, with the Germans capturing key portions of the fort, including the headquarters.
A freshly-graduated cadet armed with only a TT pistol, Pluzhnikov, with several men assisting him, managed to successfully reoccupy the headquarters and eliminate one of the German machine-gun nests.
When the invaders bombard the fortress with artillery, Pluzhnikov takes cover in the basement where Mirra and three soldiers (starshina Stephan Matveevich, junior sergeant Fedorchuk and private Vasyliy Volkov) are waiting for the fighting to end.
He heroically charges Germans holed in one of the fortress towers and thrust himself inside holding a grenade.
Pluzhnikov continues to make sneak attacks on Germans and learns how to move silently and stealthily along the fortress corridors.
When Pluzhnikov sais that he will not go without his wife, they begin to insult him and make mocking speculations about his and Mirra's sexual relations.
Pluzhnikov tries to shoot him but only kills a couple of his guards, as his eyesight is deteriorating due to days spent in the dark basement.
Instead, the Germans decide to send a Jewish captive, former violinist Ruvim Svitsky from the Brest ghetto, inside the basement.
He offers Pluzhnikov a chance to surrender and says if he refuses, Svitsky's family will be shot by Germans and the basement will be burned out by flamethrowers.
Half-blind, exhausted, starving and mentally defeated, Pluzhnikov chooses to surrender to save the Svitsky and his family.