一文字秀虎（仲代达矢饰）征战多年，手段残忍。在七十岁时，秀虎准备将家业一分为三，由三个儿子分掌大权。他把太郎孝虎（寺尾聪饰）、次郎正虎（根津甚八饰）、三郎直虎（隆大介饰）叫到跟前，以“支箭会断，砚支箭折不断”喻语告诫三兄弟，嘱咐他们要休戚与共。三郎当场把三支箭横在膝上折断，以抗议父亲枉经乱世，而不知人情。秀虎大怒，将三郎驱逐出境。三郎遂到邻国入赘为婿。 　　而之后一文字家果然被三郎言中，背信弃义的告诫果然成真，父子及兄弟间的纷乱开始，迎接他们的将是什么命运？Japanese warlord Hidetori Ichimonji decides the time has come to retire and divide his fiefdom among his three sons. His eldest and middle sons - Taro and Jiro - agree with his decision and promise to support him for his remaining days. The youngest son Saburo disagrees with all of them arguing that there is little likelihood the three brothers will remain united. Insulted by his son's brashness, the warlord banishes Saburo. As the warlord begins his retirement, he quickly realizes that his two eldest sons selfish and have no intention of keeping their promises. It leads to war and only banished Saburo can possibly save him.