Plot Summary:During the time of change of the mid-19th Century, Yaichiro is bid farewell by his fellow samurai friends Munezo and Samon as he leaves their clan's fiefdom on the northwest coast of Japan (Unasaka) to take an important position within the shogunate in far away Edo. Munezo has lived modestly with his mother and sister Shino after his father was forced into suicide after the failure of a bridge project. Kie, a farm girl serves them as a maid in their house. As time passes, Munezo's sister marries Samon, his mother dies, Kie is married into a merchant family, and he is required to learn western methods of warfare such as the use of artillery and firearms from an official sent from Edo. Learning that Kie is ill due to abuse, he rescues her from her husband's family. Although sharing mutual affection and respect, a marriage between Munezo and Kie is still impossible due to different castes, and when he, now a bachelor, is criticized for her serving in his house, Munezo sends her back to her father's farm. After being caught in a failed political intrigue, Yaichiro is sent home in disgrace and imprisoned in solitary confinement. After Yaichiro escapes, Munezo is ordered to prove his innocence from complicity by killing his old friend, and he seeks the help of his old teacher, the sword master Kansai Toda. Although Yaichiro had been the better swordsman when they studied together, Toda entrusted the secret of the "Hidden Blade" only to Munezo. Toda now teaches him a new technique to use as he prepares to face Yaichiro, who has taken hostages in a farm house.
时值德川幕府末期，海坂藩的下级武士片桐宗藏（永濑正敏 饰）和母亲（倍赏千惠子 饰）、妹妹志乃（田畑智子 饰），以及女佣希惠（松隆子 饰）过着清贫但安乐的生活。母亲过世后，妹妹嫁给了宗藏的好友岛田左门（吉冈秀隆 饰），而希惠却有个不好的婆家。 一日，宗藏偶与希惠在街头重逢，在得知她 倍受婆家人的欺虐后，他怒不可言，将她背回家中收留养病。宗藏心中对希惠尘封已久的爱恋又重新点燃，但他出于各种顾忌，却没敢表明真心。终于，希惠还是离开了宗藏回到家中。而宗藏的同门师兄弟兼好友狭间弥市郎（小泽征悦 饰）因秘密谋反，被捕后越狱出逃，宗藏受命前去追讨。身怀独门秘技隐剑鬼爪的宗藏，将与弥市郎展开一场生死之搏。
