Infinity Blade III is an action role-playing game for iOS, developed by Chair Entertainment and Epic Games. It is the third game in the Infinity Blade series of video games. It was released on the App Store on September 18, 2013. The main characters of the game are Siris and Isa, and it is intended to be the final game of the Infinity Blade trilogy.

In an introduction, the Worker of Secrets narrates about his immortal creations, the Deathless, and their wrath on humanity. He forges the Infinity Blade, the only weapon that can permanently kill Deathless. He was betrayed by a Deathless, the ruthless Ausar the Vile, who took the Infinity Blade for himself, and locked the Worker away in his Vault of Tears. The God King, Raidriar, used the Blade to enslave humanity until he was defeated by Siris, who is a reincarnation of Ausar with no memory of his previous life. Siris, having used the Blade to kill Raidriar, unknowingly activated the Blade's potential to permanently kill the Deathless. Siris later frees the Worker, who traps him and Raidriar in the Vault of Tears and continues his plan to destroy the world to build a new one.

Having escaped the Vault in Infinity Blade: Redemption, Raidriar, armed with the Infinity Blade, confronts the Worker, and realizes that he has been creating more Infinity Blades to keep the Deathless busy while he enacts his plan. After he defeats Raidriar in battle, the Worker clarifies his plan to "cleanse" the planet — to destroy all in the planet and start anew — and offers Raidriar a chance to join him. Raidriar refuses and, knowing Siris is the only one who can defeat the Worker, sacrifices himself by teleporting the Worker's datapad away. Infuriated, the Worker impales Raidriar with an Infinity Blade, permanently killing him. Meanwhile, Siris' companion Isa is revived as a Deathless following an attack by the Worker.

Siris travels to Raidriar's castle to retrieve the datapad, but he realizes that he has been replaced by a soulless Raidriar, who is killed by Siris. After retrieving the datapad and the soulless Raidriar's weapon, the Infinity Cleaver, he returns to Isa, where the two theorize that the Worker has been forging more Infinity Blades. Isa ventures to the desert, where she uncovers a vault which was used to store all the Infinity Blades, and gains information from Terrovax, the High Lord of House Burke, about the other weapons. Isa rescues Siris' childhood friend, the blacksmith Jensen, from a heavily disfigured Thane, while Siris defeats Therin, "the Killer of Dreams", and retrieves the Infinity Spear. Isa is defeated in a battle with Lelindre, "the Mistress of the End", but she is spared by her and is given the Infinity Daggers. Meanwhile, Siris returns to the Vault of Tears to retrieve the Redeemer, the device that was used to erase his memories as Ausar, and asks Jensen to reprogram it for another purpose.

Siris and Isa head out to the Worker's lair and fight their way through, including the dragon Ba'el. Isa battles and defeats the soulless Raidriar, while Siris faces the Worker to stop him from boarding his ship and wiping out all life in the world. After an intense battle, the Worker parries away Siris' weapon, and holds him by the neck, telling him that he will "unmake the world as he please, just like he will unmake him." However, Siris twists around and sends the Infinity Blade into the Worker's chest. The Worker mocks him, as the weapon will not kill him permanently, but Siris inserts the Redeemer inside the blade, erasing the Worker's memory. As the Ark self-destructs, Isa saves Siris by teleporting him back to the Hideout, and the world is saved.

In the post-credits scene, Siris and Isa encounter a child that is building a sand castle that resembles the Ark. This child is presumed to be the Worker, reborn as a child with his memories erased. less