Plot
Childhood friends and samurai commanders Washizu and Miki are called to the Spider's Web Castle, the estate of local lord Tsuzuki, after defeating the lord's enemies in battle. On their way through the Spider's Web Forest, they encounter an evil spirit who foretells their future. The spirit informs them that Washizu will be named Lord of the Northern Garrison and Miki will become commander of the first fortress that day, that Washizu will later become Lord of Spider's Web Castle, and that Miki's son Yoshiteru will eventually become lord.
When the two reach the castle, Tsuzuki rewards them with exactly what the spirit had predicted. As Washizu discusses the events with his wife Asaji, she convinces him to murder Tsuzuki when he visits. She offers drugged sake to Tsuzuki's guards, incapacitating them and allowing Washizu to kill Tsuzuki with a spear. She then frames an unconscious guard, who is killed by Washizu in the ensuing chaos. Both Kunimaru, Tsuzuki's vengeful son, and Noriyasu, one of Tsuzuki's advisors, suspect Washizu's treachery and try to warn Miki, but Miki refuses to believe them.
Under Asaji's influence, Washizu comes to question Miki's loyalty but nevertheless chooses Yoshiteru as heir, as he and Asaji have no child of their own. Washizu plans to inform Miki and Yoshiteru about the decision at a grand banquet, but Asaji reveals that she is pregnant, leaving him in a quandary. He eventually decides to eliminate Miki and Yoshiteru.
At the banquet, an agitated Washizu drinks sake copiously as the guests await Miki and Yoshiteru's arrival. He hallucinates and sees Miki's ghost and, in a delusional panic, reveals what has transpired by exclaiming that he is willing to slay Miki a second time, unsheathing his sword and slashing at Miki's empty seat. Asaji has the guests dismissed. One of Washizu's men arrives carrying a bundle containing the severed head of Miki, and informs the couple that Yoshiteru has escaped. Washizu kills the man in a fit of anger.
As Washizu grows increasingly paranoid and tyrannical, his men begin to doubt and fear him, and rumors circulate that Yoshiteru, Kunimaru, and Noriyasu have joined forces with their onetime rival Inui. Washizu is distraught by the news that his heir has been born dead. In order to ascertain the outcome of the impending battle, he returns to the forest in search of the evil spirit. The spirit tells him that he will not be defeated in battle until "the trees of the Spider's Web Forest rise against the castle", leading him to believe that his victory is all but assured.
The next morning, Washizu finds Asaji in a semi-catatonic state, trying to wash clean an imaginary stain and stench of blood from her hands. He is then told by panicked soldiers that the trees of Spider's Web Forest have risen to attack them. A desperate Washizu tries to muster his troops, but they ignore his commands and fire arrows at him, severely wounding him. When Washizu tells them that to kill their lord is treason, they accuse him of having done the same. As his enemies approach the gates, he succumbs to his wounds, attempting to draw his sword as he dies. It is then revealed that the attacking force had used trees, cut from the forest during the night, to shield their advance onto the castle.
