Dimensional Prison is the first stage of Lords of Shadow Chapter 14. Gabriel Belmont, now a vampire and having entered the dimension housing the Forgotten One, seeks out the demon to finally destroy it, traveling through a cavernous region.
"And so I entered the dimensional rift, seeking the Forgotten One. The air was thick with death and decay. Poor Laura had told me that this place was not for humankind, but I was no longer human and any vestiges of my humanity were now gone from me entirely. I hungered for revenge. Darkness consumed me. Rage drove me. All those people who had died or suffered at my hand were but a distant memory now. I wanted blood. The demon would feel my wrath this night, would feel the bitter taste of defeat at my hand and I would crush his soul to dust beneath my feet. The terrible path of my destiny was now laid before me and with absolute clarity of mind, I walked that path paved with the corpses of my enemies and friends alike with relish."
Newly made a vampire and with his left eye concealed, Gabriel emerges within the prison, a rock-hewn cavern. After destroying a troop of Reapers and Swordmasters, he comes to a sealed door with a weak area at the very bottom. Using the Vampire Killer, Gabriel breaks open the bottom of the door and continues on. He soon comes to a pool of molten lava, but upon approach Gabriel doubles over in pain as the Forgotten One, a gigantic demon in silvery-white armor, emerges from the pool. Before it has a chance to see him, Gabriel conceals himself behind a boulder, his pain easing as the Forgotten One moves away from him.
Gabriel silently follows up after the demon as it climbs up the walls and tries to break through the ceiling of the chamber, which is a metal structure secured with chains. However, the Forgotten One senses something underneath him, prompting Gabriel to quickly hide in order to avoid being detected. The demon proceeds to break the chains and go on its way to the dimension's exit, but the disturbance causes the lava pool to begin rising up after the both of them. Gabriel outruns the magma by rapidly scaling walls and running up wooden platforms. The Forgotten One is unaffected by the lava, however, and keeps going; Gabriel is encouraged to hide again when the demon catches up to him. A second series of chains is destroyed by the enormous creature, yet due to its efforts, flaming rocks begin raining down on Gabriel, who dodges them to avoid being knocked down into the rising liquid.
The Forgotten One attempts to keep ascending, but grabs hold of a metal support which bends too far back and causes the demon to fall back into the lava under Gabriel. As the molten rock doesn't affect it, the Forgotten One reemerges and climbs back up, but this time beneath Gabriel, which spurs the former knight into moving upwards. The Forgotten One's ascent creates handholds for Gabriel, and surprisingly the demon has not seen him yet.
Reaching the summit, the giant fiend uses its power to pry open a circular door, but the effort appears to momentarily weaken him. Waiting for the right moment, Gabriel rushes at the Forgotten One, but is noticed by the demon, who grabs and then throws Gabriel. The two fight, and Gabriel is able to wound the Forgotten One's right knee, stripping it of its armor and exposing glowing muscle. Surprised to see a human in the dimensional prison, the Forgotten One recognizes Gabriel's armor as belonging to the Brotherhood of Light. It notes that there is something different about Gabriel, who vows to destroy the Forgotten One. The fiend only laughs at Belmont's words and informs him that a part of its own power is obliterating the seal on the prison. The demon also promises to "strip the living flesh" from Gabriel's body and "devour" his soul.
A battle ensues between them. The Forgotten One uses shockwaves, flares, and a pair of serrated shadow blades to harm Gabriel; attacks that hit greatly drain Belmont's life. However, the knight is able to weaken the demon, particularly by attacking the exposed knee and deflecting the flares back. He rushes the demon again and is able to cling to its back, successfully destroying the armor of the Forgotten One's torso with several punches. He additionally is able to hit the demon with its own rock mace, but at that moment the cavern trembles, pieces of rock falling around them. The Forgotten One acknowledges Gabriel as a "worthy rival", but insists that he will not win. Gabriel impatiently dismisses the creatures words, but the Forgotten One recalls his power from the door, which has been successfully broken through.
Gabriel retreats behind a boulder once again, while the Forgotten One laughs and insists the warrior kill himself while he has the opportunity, promising that he will suffer, never finding peace "in Light nor Darkness". The Forgotten One then leaves the chamber through the door it has unsealed, continuing to the rift's exit.