A sudden attack by Wulf, a clever and traitorous lord of Rohan seeking vengeance for the death of his father, forces Helm Hammerhand, the King of Rohan, and his people to make a daring last stand in the ancient stronghold of the Hornburg.
Set 183 years before the events chronicled in the original trilogy of films, it tells the fate of the House of Helm Hammerhand, the legendary King of Rohan. A sudden attack by Wulf, a clever and ruthless lord of Rohan, with dubious ancestry, having many ties to Dunland, he seeks vengeance for the death of his father, forces Helm and his people to make a daring last stand in the ancient stronghold of the Hornburg-a mighty fortress that will later come to be known as Helm's Deep. Finding herself in an increasingly desperate situation, Héra, the daughter of Helm, must summon the will to lead the resistance against a deadly enemy intent on their total destruction.—Warner Bros. Pictures
The narrator called Eowyn narrates the tale about, Hera, Helms daughter who is a warrior, as she rides towards a mountaintop, feeding the nearby eagles in the process. Upon her return to Edoras, Hera comes across her brother Hama singing a saga. She also meets Haleth, her other brother and her cousin Frealaf.
A dunlending lord with Rohrirric blood, named Freca arrives at Helms hall with Wulf, who she plans to marry to Hera but she isn't interested. Freca then complains about the possibility of Hera becoming married to a Gondorian lord, making Rohan weaker. Helm becomes wary and believes that she is only interested in seizing the throne. Helm and Freca fight outside and Freca is unintentionally killed. Wulf grows upset.
Wulf goes out wandering for years, while Hera worries. One day, Hera and Frealaf come across a dead Southron warrior and tamer of the mamasks. Hera gets rid of it in a lake, before stirring it and a giant watcher eats up the body. Unfortunately, Hera is kidnapped by Targg. Targg takes Hera to Wulf stronghold and it is revealed that Wulf has become lord of the dunlending rebels, as he cuts her face on purpose after accidentally cutting it when they were younger. She offers to marry him, in the hope that he stops attacking Rohan, but she is rescued by Frealaf and her aunt.
Whilst Wulf goes to attack Rohan, Helm assumes that Frealaf failed to protect Hera, but Frealaf heads for Dunharrow. Helm preps for battle and Lord Thorne raises men. The Paige, Leif delivers a scroll belonging to Thorne and it has a seal looking just like Wulfs. Hera discovers that Thorne has become a traitor. Thorne attempts to kill her, but she executes him on her horse, before getting Eudoras out, since Wulfs army is coming for them.
Haleth kills a mumak, just before Wulf kills Haleth and he has Hama captured. Hamas horse had given up and Helm offers to surrender from the war to protect Hama and spare Hamas life, but Wulf cuts Hamas throat. Wulf builds gigantic siege equipment. Despite being injured, Helm still manages to sneak out to kill Wulfs army. Hera follows in hot pursuit and they come across, ring-collecting orcs and a horned troll in the journey. Hera and Helm kill the troll, but Helm refuses to follow Hera back into the lair. However, Helm tells Hera that she has enough strength to become queen. Unfortunately, Helm is killed in the pursuing battle outside, freezing while standing up.
Hera gives an eagle Helms paraphernalia and tells it to fly off and get Frealaf to help. The Supply-keeper, Old Pennicruik hands Hera a bridal dress. She Dons the gown, before riding off to a drawbridge, which Wulf had lowered to invade Hornburg. She challenges Wulf to fight, to distract him from the Rhoanites sneaking into the out passage. The duo battle and Hera defeats Wulf, by making him surrender. Taragg agrees with Hera and this causes Wulf to murder him.
Frealaf and his henchmen arrive and he uses Helms horned armour to frighten the Dunlendings into believing that his spirit is roaming free, making them all run away. Meanwhile, Wulf uses a knife on Hera and her Aunt, Olywn throws her a shield, which she uses to choke Wulf, ultimately killing him.
Helm becomes the namesake for the stronghold, Helms Deep. Saruman becomes the new keeper of Isengard and Frealaf becomes king of Rohan. Hera however has very little interest in ruling over people, goes off with Olwyn, seeking adventure. Hera meets Gandalf and he has questions about the orcs she had encountered. The narrator informs the audience that Hera was free to roam until the end of her days, carrying Hamas harp.
