昭和20年（1945）8月，在这个最热的夏天，日本帝国正面临着落败的终局。陆军大臣阿南惟几（柴俊夫 饰）等5名军方高层意识到败局已定，为了替将来的复兴做准备，他们决定将“马来之虎” 山下奉文从麦克阿瑟（约翰•萨维奇 饰）手中夺取的900亿日元黄金藏匿起来。承担这一绝密重任的是陆军近卫第一师少佐真柴司郎（堺雅人 饰）、中尉小泉重雄（福士誠治 饰）以及经历了血雨腥风的曹长望月庄造（中村狮童 饰）。他们奉命将黄金伪装成号称终极武器的决号榴弹，在森胁女子学校20名少女的帮助下藏进了某山洞中。在这一过程中，军人和女孩们建立了信任与友情，但残酷的战争却将他们引向了黑暗的终点……
本片根据浅田次郎的同名原著改编。

Mikio is a married man and works hard for the company where he is employed. Then one day Mikio is diagnosed with depression. Mikio's wife is Haruko. They have been married for 5 years. Haruko draws comics for work, but they do not sell well. She mainly relied on Mikio for support. Meanwhile, Haruko did not notice any changes in her husband. She begins to blame herself for not noticing any signs. Mikio's depression derived from his work. His company has been pressing him to quit the company. After Mikio quits his job his condition improves, but the dynamics of their relationship changes.