Flash battles satanic swordsmen and other samurai.
The Flash is caught between the ruthless Baron Katana and his indestructible swordsman, Daisho. In Tokyo, Picture News reporter, Iris West, looks for a way to cover her husband's absence, without revealing his secret identity to police captain Hashi, his assistant, Tushi, or filmmaker Hideki Toshira. Hashi is planning to approach Baron Katana's island fortress, known as "The Black Heron", under the guise of a film crew. Hashi gathers his elite Black Beret forces, and makes plans to assault the Black Heron. The Flash makes a run for it. Vibrating at super-human speed, the Flash dives through a wall, only to smack hard into one of Baron Katana's robot soldiers.
The Samuroid drags the dazed speedster back to Baron Katana. The Flash is stung up over the cliffside of the Black Heron. The ropes binding him are attached to buckets, floating on the sea. As the tide rises, the buckets fill with water, hyper-extending the Flash arms. Baron Katana issues attack orders to his Samuroids. At the same time, Hashi is issuing attack orders to his Black Berets. West presents her "husband" to Hashi. Concealed under a wide-brimmed hat and wearing a trench coat, West's "husband" feigns laryngitis, so as not to speak in front of Hashi. Toshira outfits the Black Berets in samurai armor.
Despite the agony of his torture, the Flash refuses to divulge any information to Baron Katana. Hashi's forces land on the Black Heron, and move about the perimeter, acting, for all to see, as a film crew shooting on location. Fearing discovery before he can launch his surprise attack on Japan, Baron Katana has the Flash brought into the fortress, and caged in a cell. Breaking away from Hashi's forces, West begins scaling the cliffside of the Black Heron, intent on rescuing the Flash. West's "husband" goes after her. With West breaking the illusion of their strategy, Hashi orders his forces to immediately assault the Black Heron.
West and her "husband", really Tushi in disguise, are taken prisoner by the Samuroids. West's screams spur the Flash to action. The Flash breaks free, and after destroying the Samuroid guard, takes possession of it's sword. Upon scaling the cliffside, Hashi's forces are met by the Samuroids. The Black Berets open up with flamethrowers, but the Samuroids are unaffected. The Samuroids repel Hashi's forces, leaving them dangling down the cliffside by their ropes. The Flash storms Baron Katana's control center, but stops short when he realizes West and Tushi are being held hostage. Daisho gives the order for the Samuroids to slay Hashi's forces.
Moving faster than the speed of light, the Flash races out of the control room. Rushing past the Samuroids creates a vacuum that extinguishes their jet packs, causing them to fall into the sea. The Flash returns to the exact spot he was standing, with no one the wiser that he ever moved. Tushi suddenly kicks Baron Katana, giving the Flash the opening that he needs. The Flash kicks Daisho into the control panel, shorting out all of the Samuroids. Baron Katana leaps to his death, rather than face imprisonment. West gets the Flash into the clothes her "husband' was supposedly wearing, before they rendezvous with Hashi. Tushi appears wearing Toshira's armor, claiming that she, surreptitiously, came along on the assault. The Flash, as police forensics scientist, Barry Allen, agrees to keep Tushi's secret, in return for her keeping his identity as the Flash a secret.